Ultrafast Structural Dynamics of Molecular and Biomolecular Systems

Observing molecular dynamics experimentally with both, highest spatial and temporal resolution is one of the biggest challenges in chemistry and biochemistry. Understanding and resolving structure-dynamics relationships will help to further understand molecular function. Few experimental methods allow to resolve multi-scale dynamics and structural information in the same experiment. [more]

An Atom's Eye View of Electrochemical Energy Transformations

The transition away from fossil fuels will provide the defining challenge for the next generation of chemists and engineers, and electrochemical technologies are crucial for this transformation. By providing a link between (renewable) electricity sources and chemicals, these technologies allow not only for storage and transportation of energy, but also provide routes to synthesize a wide range of chemicals and materials that today are integrally reliant upon fossil fuels. [more]

Single photon hot electron ionization of fullerenes

The separation of the time scales of electronic and nuclear motion in clusters and molecules opens the possibility that the electrons can form a transient and highly excited subsystem coexisting with cold nuclear degrees of freedom. [more]

Machine Learning Models of Many-body Atomic and Electronic Interactions

[more]

Vibrational Circular Dichroism of Molecular Crystals: The Interplay of Symmetry and Chirality

Chiroptical spectroscopy provides an increasingly important, cost-effective alternative for the study of chiral substances in the solid state. In recent years, vibrational circular dichroism (VCD) – the chiral form of IR absorption spectroscopy – has come into focus as a very sensitive probe of molecular conformation and environment. [more]

Electrochemical surface science of platinum electrodes

This talk will discuss recent insights into the electrochemistry of platinum, highlighting three topics. [more]

Tuning the Polarity of Porous Materials to Impact Adsorption, Diffusion, and Catalysis

Ordered mesoporous (organo)silicas provide a highly tunable platform to modulate the hydrophobicity of their surfaces, through thermal control of surface hydroxyl density as well as the incorporation of organic framework linkers. [more]

Scientific defense

In situ and operando Electrocatalysis: Shape-dependent Nanocatalysts for the CO2 Reduction and the Formic Acid Oxidation
[more]

Rovibronic Transitions in Molecules: Toward an Exact Approach

Molecules exhibit complex structural and dynamical behavior manifested in their degrees of freedom. The common approach to help us understand this complexity is to start with a zero-order approximation. Beyond the zero-order picture, the voyage to explore the molecular world is just about to begin. [more]

Scientific defense

Operando Insights into Size and Shape-controlled Cu-based Nanocatalysts for the Electrochemical Reduction of CO2 toward C2+ Products
[more]

Semiconductors and Topological Insulators for Infrared and Terahertz Metamaterials

When working in the infrared (IR) or terahertz (THz) spectral ranges, traditional optical materials like gold and silver have extremely large and negative permittivities. This means it is difficult to use these materials for plasmonics or hyperbolic metamaterials, both of which require materials with relatively small and negative permittivities. We must therefore explore alternative materials. In this talk, I will focus on two classes of materials: heavily-doped III-V semiconductors for the IR and topological insulators for the THz. [more]

Twisted Tessellations - Coherent Control of the Translational and Point Group Symmetries of Crystals with Light

Advances in mid and far-infrared THz sources have created a new paradigm in condensed matter physics: ultrafast structural and functional control through direct lattice excitation. Striking changes in magnetism, metallicity, ferroelectricity, and superconductivity, observed experimentally on ultrafast timescales, have been tied to the anharmonic coupling between pumped infrared-active (IR) phonons and Raman-active phonons via the nonlinear phononics effect. [more]

Hydrogen-Involved Surface Processes on Model Catalysts

The first topic of this talk is focused on the atomic-scale processes of dissociative adsorption and spillover of hydrogen on the single atom alloy catalyst (SAAC) Pd/Cu(111) [1]. The hydrogen spillover on the Cu(111) surface from the Pd site was successfully observed in real-time using infrared reflection absorption spectroscopy (IRAS) at 80 K. The observed chemical shifts of Pd 3d5/2 in X-ray photoelectron spectra (XPS) indicate that H2 is dissociated and adsorbed at the Pd site initially. [more]

Ultrafast Exciton Dynamics in Moiré Heterostructures: a Time-resolved Momentum Microscopy Study

Transition metal dichalcogenides (TMDs) are an exciting model system to study ultrafast energy dissipation pathways, and to create and tailor emergent quantum phases [1,2]. The versatility of TMDs results from the confinement of optical excitations in two-dimensions and the concomitant strong Coulomb interaction that leads to excitonic quasiparticles with binding energies in the range of several 100 meV. [more]

2D Silicates from Ultimate Membranes to Robust Ferromagnets

Silica deposited onto late transition metal surfaces spontaneously forms a 2D van der Waals structure constructed of mirror image planes of rings of corner sharing SiO4 tetrahedra with crystalline and amorphous polymorphs possible. The silica can be deposited by an atomic layer deposition (ALD) process, opening the door to applications. [more]

From Levinthal’s Paradox to the Enigma of Disappearing Polymorphs: Using Minima Hopping to Explore the Synthesizability and Stability of Materials

Each local Minimum on the potential energy surfaces corresponds to a stable structure. In a theoretical structure search one typically finds a number of low energy minima that is much larger than the number of experimentally known structures. [more]

Things MOFs do, a Journey Skirting the Edges of Sanity

Metal Organic Frameworks, or MOFs for short, are a class of materials that consist of organic molecules that link together metal centres to form an ordered, often porous solid. This multi-component nature affords MOFs a great versatility in terms of their internal structure and properties and thus a wide array of potential use cases. Unfortunately, at least from the point of a theorist, their metal-organic nature also makes them a pain in the neck to treat. Especially when comparing theoretical results to experiment it often turns out that MOFs are significantly less well behaved than advertised. [more]

Fritzn's Wiesn - FHI Sommerfest 2023

Die Abteilung Theorie läd zum diesjährigen FHI-Sommerfest, einem preußisch-bayerisches Sommerfest unter dem Motto “Fritzn's Wiesn” ein. [more]

Fritzn's Wiesn - FHI Summer Party 2023

The Theory Department invites you to this year's FHI Summer Party, a Prussian-Bavarian summer festival with the motto "Fritzn's Wiesn". [more]

Polaritonic Metasurfaces

In this talk, I discuss our recent efforts in the context of nano-optics and photonics, with a special emphasis on strong light-matter interactions enabled by excitonic, phononic, electronic and magnonic material responses coupled to engineered metasurfaces. I will discuss our recent theoretical and experimental results in the context of polariton manipulation in these systems, the role of symmetries in their control, and their opportunities for technological advances. The combination of these features with photonic engineering enables giant optical nonlinearities, efficient nanoscale light manipulation and topological wave phenomena. During the talk, I will discuss the exotic light-matter interactions arising in these systems, and their opportunities for wave physics and photonics technologies. [more]

From Heavy Elements to Peptides: Dynamics, Kinetics, and Thermochemistry

In this presentation, I will review recent studies that utilize guided ion beam tandem mass spectrometry to examine the kinetic energy dependence of ion-molecule reactions. [more]

Light, Tips and Molecules: SPM on the Path to Direct Nano-Optical Measurements

Exploration of essential photophysics at the level of individual molecules and atoms requires highly specialized optical spectroscopies that work at the very limit of instrument sensitivity or have to use plasmonic nanostructures - in order to overcome the fundamental resolution limits achievable with visible and infrared light. [more]

AI-Accelerated Organic Chemistry

AI-accelerated Organic Synthesis is an emerging field that uses machine learning algorithms to improve the efficiency and productivity of chemical synthesis. [more]

Superradiance in waveguide-coupled atomic ensembles

The power of the light emitted by a single, excited quantum emitter features a characteristic exponential decay. However, the presence of other, identical emitters can substantially alter the decay dynamics of the ensemble. Such collectively enhanced emission is termed superradiance, and has seen increased interest over the last decade due to its potential applications in quantum technology and metrology. [more]

Excited-electron mediated defect diffusion, secondary electrons, and problems withthermalization

In this talk, I will present on our simulation work of using electronic excitations, induced by laser or ion irradiation, to trigger defect mobility. [more]

Optical Probing of Ordering in Solid-State Materials

Symmetry and its breaking sit at the core of condensed matter physics research and determine the ordering and unique functionalities of solid-state materials. Ultrashort light pulses from visible to THz wavelength ranges offer the opportunity to probe and control the electronic, phononic, magnetic, and even time ordering in those materials. [more]

Gapless Detection of Broadband Terahertz Pulses Using a Metal Surface in Air-based on Field-induced Second-harmonic Generation

We investigate second-harmonic generation (SHG) light from a Pt surface in air under terahertz (THz) pulse irradiation. THz pulse-modulated SHG intensity shows a clear time profile of the THz field. [more]

Light-Matter Control of Quantum Materials

  • PC Department Seminar
  • Date: Aug 28, 2023
  • Time: 11:00 AM (Local Time Germany)
  • Speaker: Michael Sentef
  • University of Bremen & MPI for the Structure and Dynamics of Matter, Hamburg
  • Location: Building G
  • Room: 2.06
  • Host: Melanie Müller
Advances in time-resolved pump-probe spectroscopies have enabled us to follow the microscopic dynamics of quantum materials on femtosecond time scales. This gives us a glimpse into the inner workings of how complex, emergent functionalities of quantum many-body systems develop on ultrafast time scales or react to external forces. [more]

Theory of Higgs Spectroscopy: How to Activate and Detect the Higgs Mode

  • PC Department Seminar
  • Date: Sep 27, 2023
  • Time: 11:00 AM (Local Time Germany)
  • Speaker: Dirk Manske
  • Max Planck Institute for Solid State Research, Stuttgart
  • Location: Building G
  • Room: 2.06
  • Host: Martin Wolf
Higgs spectroscopy is a new and emergent field that allows to classify and determine the superconducting order parameter by means of ultra-fast optical spectroscopy. There are two established ways to activate the Higgs mode in superconductors, namely a single-cycle ‘quench’ or an adiabatic, multicycle ‘drive’ pulse. [more]

30 Years of the Chemical Weapons Convention (CWC): Histories, Achievements, Challenges

The countdown has begun for the upcoming conference, "30 Years of the Chemical Weapons Convention (CWC): Histories, Achievements, Challenges," scheduled to take place on October 5-6, 2023 in Harnack-Haus in Berlin. The conference is supported by the Fritz-Haber-Institut der Max-Planck-Gesellschaft, the Universität Hamburg, and the CWC Coalition of the Arms Control Association. [more]

Electron-Phonon Coupling from First-Principles

For this talk, I will highlight the importance of electron-phonon interaction to describe many experimental phenomena including carrier mobility, phonon-assisted optical absorption, phonon-limited superconductivity, zero-point renormalization, temperature dependence of the bandgaps, electron mass enhancement and polaron liquids.I will show how to derive and efficiently compute electron-phonon interaction from first principles focusing on two manifestations of the electron-phonon coupling: carrier mobility and temperature dependence of the bandgap. [more]

Tailoring thin films for catalysis: Thin film growth methods and properties

CatLab Lectures 2023/2024
Thin film technology is a key technology in many high tech sectors today and plays a crucial role in the development of photovoltaics. It allows to control of a very broad set of material (e.g.electronic or optical) properties down to the atomic level, yet can be compatible with high-volume low-cost manufacturing. The Catlab project aims to exploit exactly these characteristics of thin film technology for use in catalytic reactions, especially for chemical energy carriers, such as (green) hydrogen and carbon- or nitrogen-based chemicals derived from it. [more]

Modelling catalyst degradation through experiment and computation

CatLab Lectures 2023/2024
Catalysts degrade over time during reactor operation, resulting in loss of activity, as well as selectivity. A variety of physical and chemical phenomena contribute toward catalyst degradation, such as particle growth, coking, poisoning, or chemical reactions between the catalyst and the reaction medium, or between the active material and the catalyst support. Catalyst degradation is not always well-understood, and improving a catalyst's life time is often a trial-and-error process. This lecture will cover the fundamental causes of typical catalyst deactivation phenomena, introduce computational and experimental techniques to analyze catalyst degradation, and demonstrate practical examples to a rational approach to make catalysts more resistant to degradation. [more]

Watching Femtosecond Molecular Dynamics using Synchrotrons and X-Ray Free-Electron Lasers

Recording real-time movies of dynamical processes in molecules, as, for example, progressing chemical reactions, has been a driving force for many disciplines in fundamental sciences during the last decades. Comparably new are experimental techniques, that address single molecules in the gas phase and that involve coincident single-particle detection for imaging these dynamics are Coulomb explosion imaging and Photoelectron diffraction imaging. [more]

Model systems in catalysis research

CatLab Lectures 2023/2024
Model catalysts are specifically designed to address the complexity issue in catalysis. Real catalysts are very complex, which makes them a nightmare for scientists seeking to understand how these systems work. Typically, only a small part of the catalyst’s compositional and structural spectrum is relevant for the catalytic process. Consequently, much of the spectral and structural information stems from irrelevant parts of the catalyst, making the identification of relevant components a non-trivial and error-prone task. [more]

Combining Experimental and Theorical Data for Accurate Predictions and Mechanistic Insights in Heterogeneous Catalysis

First-principles prediction of heterogeneous catalytic performance is challenging due to the complexity of real catalysts and their evolution over time. But even for simple model catalyst surfaces, chemical accuracy (or sufficient accuracy to discriminate the rates of many potentially competing mechanisms) in predictions of reaction energetics on transition metal surfaces is lacking due to difficulties in simultaneously describing metallic states in the catalyst and molecular adsorbate states and the interactions between them. [more]

Microwave absorption: Operando EPR and MCPT as tools to characterize heterogeneous gas phase catalysts

CatLab Lectures 2023/2024
It is well established that many heterogeneous catalysts encounter substantial changes of their properties if comparing the catalyst under turn-over conditions with those found ex-situ. These changes encompass not only structural but also electronic properties rendering a detailed characterization still challenging. A variety of characterization techniques have been developed in recent years toinvestigatecatalytic systems under operando conditions. In this respect it is important to realize that none of these methods allows to obtain a complete picture which requires on the one hand the combination of different techniques and on the other hand knowledge about available techniques and their potential use and their limitations. [more]

OPERANDO SPM 2023

The OPERANDO SPM 2023 conference aims at bringing together scientists, engineers and students with an interest in operando measurement techniques, including scanning probe microscopy (SPM), spectroscopy, and related modelling. [more]

How do chemical bonds break in ultrastrong coupling?

Current efforts for implementing cavity QED in the ultrastrong coupling (USC) regime using molecular vibrations in mid-infrared nanoresonators opens exciting opportunities for exploring novel chemical reactivities that exploit quantum correlations with the electromagnetic vacuum at room temperature. [more]

Operando Electron Microscopy

CatLab Lectures 2023/2024
Heterogeneous catalysis is considered one of the key technologies in prospective energy conversion scenarios. Yield, efficiency, and lifetime of heterogeneous catalysts will become of utmost importance and the demand of novel high-performance catalysts fulfilling the above- mentioned criteria will rise tremendously. To cope with the prospective high demand for these functional solids, current catalyst development approaches that are based on empirical optimization may become insufficient and should be replaced by knowledge-based catalyst design strategies. [more]

Lithium, Interfaces & Action: Desiging Solid Battery Materials

Next generation of energy storage devices may largely benefit from fast and solid Li+ ceramic electrolyte conductors to allow for safe and efficient batteries. For those applications, the ability of Li-oxides to engineer their interfaces and be processed as thin film structures and with high control over Lithiation and phases at low temperature is of essence to control conductivity. [more]

Efforts of Zhejiang University in advancing clean and sustainable energy conversion

In the presentation, a brief introduction of Zhejiang University (ZJU) and State Key Laboratory of Clean Energy Utilization will be given. An overview of China’s achievements, new goals and new measures in alignment with its Nationally Determined Contributions will be presented. [more]

Nanoparticles with Cubic Symmetry: Classification of Polyhedral Shapes

The detailed characterization of polyhedral bodies, while a subject of mathematical research since ancient times, has attracted new interest in connection with crystalline nanoparticles (NP). [more]

Applications of ICP-MS in Electrocatalysis Research

CatLab Lectures 2023/2024
Fuel cells and electrolysers require electrocatalysts to minimize losses during energy conversion processes. It is common practice that researchers rely solely on electrochemical methods to test stability in search of novel electrocatalysts. While degradation can be tracked using such methods, they fail when one aims to understand governing degradation mechanisms responsible for the losses in catalyst performance. Complementary physicochemical techniques are required. One such technique is inductively coupled plasma mass spectrometry (ICP-MS) – the main topic of my talk. [more]

Identifying the Active Site of Cu/Cu2O for Electrocatalytic Nitrate Reduction Reaction to Ammonia

Copper oxide-derived electrocatalysts are reported to have high activity and selectivity for nitrate electrochemical reduction reaction (NO3RR) to ammonia. However, the cause underlying their enhanced NH3 formation, i.e., the active catalytic site, remains unclear. [more]

Single-molecule imaging and engineering of biological and synthetic molecular motors

  • PC Department Seminar
  • Date: Nov 30, 2023
  • Time: 11:00 AM (Local Time Germany)
  • Speaker: Ryota Iino
  • Institute for Molecular Science, National Institutes of Natural Sciences, Japan
  • Location: Building G
  • Room: 2.06
  • Host: Martin Wolf
Molecular motors, an important class of molecular machines, harness various energy sources to move unidirectionally [1]. The operational principles of molecular motors are distinct from those of man-made macroscopic motors, because they have nanoscale dimensions and generally work in a solution environment where viscosity is dominant. Under these low Reynolds number, overdamped conditions, they cannot rely on inertia to sustain motion. Furthermore, they are continually agitated by random Brownian motion, which provides both challenges and opportunities for the unidirectional motion. [more]

Thin film electrocatalysts for long term energy conversion and storage

CatLab Lectures 2023/2024
Electrochemistry plays a pivotal role in our future transition to sustainable energy, particularly for the conversion of electrical into chemical energy in electrolyzers, and the reverse conversion and utilization of the stored energy in batteries and fuel cells. The common challenge in these electrochemical devices is the development of active and durable materials for the catalysis. [more]

Synthesis planning, mechanistic analysis and discovery of new reaction classes in the age of computers

  • ISC and TH Seminar
  • Date: Dec 1, 2023
  • Time: 11:00 AM - 12:30 PM (Local Time Germany)
  • Speaker: Bartosz A. Grzybowski
  • Bartosz A. Grzybowski is a Distinguished Professor of Chemistry at UNIST and a Director of the IBS Center for Algorithmic and Robotized Synthesis (CARS). He is also Professor at the Institute of Organic Chemistry, Polish Academy of Sciences. Although he has spent a large fraction of his research career on esoteric problems of self-assembly and non-equilibrium systems, he considers his most impactful discoveries to be in the area of computer-driven synthesis (e.g., the Chematica/Synthia and Allchemy programs).
  • Location: FHI library (building A)
  • Host: ISC and TH Department
After decades of rather unsuccessful attempts, computers are finally making impact on the practice of synthetic chemistry. This change is made possible by the combination of increased computing power and, above all, new algorithms to encode and manipulate synthetic knowledge at various levels, from sequences of full reactions to sequences of mechanistic steps. In my talk, I will illustrate how these advances have enabled completely autonomous planning of multistep syntheses of complex (natural product) targets, how they allow us to elucidate complex reaction mechanisms and, above all, discover new classes of reactions. [more]

Workshop on “Emerging Techniques of Nanospectroscopy Based on Scanning Probe Microscopy"

[more]

Design and characterization of integrated systems for solar fuel production

[more]

Under the Microscope - Spotlighting Materials & Nano Science

Under the Microscope a science communication project dedicated to materials and nano science. Despite the widespread relevance of materials science to everyday life, we feel that dedicated science communication in this area is much rarer than in other fields. [more]

Fast electrons and hard X-rays for unravelling atomic-scale dynamics in homogeneous and heterogeneous catalysis

CatLab Lectures 2023/2024
The increasing demand for renewable and low-cost energy motivates intensive research aimed at developing, characterizing and optimizing materials that can efficiently convert (sun) light into usable energy in the form of electricity or chemical fuels. Conventional characterization techniques either lack the spatial resolution necessary to resolve individual atoms, or they lack the temporal resolution required to capture structural rearrangements as they evolve. [more]

Molecular Simulation in the Age of AI

  • ISC and TH Seminar
  • Date: Dec 13, 2023
  • Time: 02:00 PM - 03:30 PM (Local Time Germany)
  • Speaker: Dr. Edward Pyzer-Knapp
  • Head of Research Innovation for UK and Ireland at IBM, Visiting Professor of Industrially Applied AI at the University of Liverpool, and the Editor in Chief for Applied AI Letters.
  • Location: FHI library (building A)
  • Host: ISC and TH Department
The history of chemical discovery has been punctuated by computational and theoretical developments. Evolving from empirical observation, increasingly systematised experimentation allowed for the development of theoretical underpinnings, which in turn afforded the paradigm shifting application of computational techniques, which has since co-evolved with the development of the technologies upon which they are run. Recent years have seen the emergence of data-driven techniques and technologies for building powerful models, appearing to enable us to side-step the requirement for expensive physical simulations – replacing them with highly performant, but black-box alternatives. [more]

The Exact Factorization, a Universal Approach to Non-Adiabaticity

The adiabatic approximation describes the molecular wave function as a single product of a Born-Oppenheimer state and a nuclear wave packet. This approximation is a corner stone of modern quantum chemistry and solid-state physics. It not only makes computations feasible, it also provides us with an intuitive picture of many chemical processes. [more]

Ultrafast, all-optical, and highly enantiosensitive imaging of molecular chirality

Just like our hands, chiral molecules exist in pairs of opposite “mirror twins” called enantiomers, which behave identically unless they interact with another chiral “object”. Distinguishing them is vital, e.g. as most biomolecules are chiral, but it can also be a challenging task. [more]

Understanding surfaces using probe molecules and in situ spectroscopies

CatLab Lectures 2023/2024
[more]

Time-resolved XPS for molecular electronic movies

Light excitation couples to molecular electrons. The conversion of photon energy into other molecular forms of energy is then determined by a complex interplay of electrons and nuclei, which is out of the scope of the Born-Oppenheimer approximation. [more]

Heterogeneous Catalysis as Enabler of Circular Economy

CatLab Lectures 2023/2024
The guidelines of sustainable development require a transformation of today's linear chemical industry with the aim of closed carbon cycles. In this process, renewable energy can be used as an energy/heating source and to provide chemical redox equivalents, e.g. in the form of hydrogen or electrons. Catalysts are essential to enable selective chemo-, bio-, or even electrocatalytic reactions under the dynamic supply of resources. [more]

Towards State- and Time-Resolved Fluorescence Spectroscopy of Trapped Molecular Ions

  • MP Department Seminar
  • Date: Jan 15, 2024
  • Time: 11:00 AM c.t. - 12:00 PM (Local Time Germany)
  • Speaker: Jascha Lau
  • Otto-Hahn Awardee of the Biological and Medical Section of the MPG and new Group Leader in the Department of Molcecular Physics
  • Location: Haber Villa
  • Room: Seminar Room
  • Host: Department of Molecular Physics
In this talk, I will give an overview of my postdoctoral and doctoral research, with a particular focus on anion photoelectron spectroscopy and infrared fluorescence spectroscopy, as well as the future research direction of my Otto Hahn Group in the Department of Molecular Physics, which will revolve around fluorescence spectroscopy of trapped molecular ions. [more]

Chirality differentiation and manipulation using rotational spectroscopy

Chirality is ubiquitous in nature and involved in many aspects of life, making it an important phenomenon to understand. The enantiomers of chiral molecules have identical physical properties (despite the predicted small contributions due to parity-violating weak interactions), while their chemical and biochemical properties can differ dramatically. Due to these different behaviors, the development of sensitive spectroscopic methods that can differentiate and/or separate molecules of opposite handedness, particularly in complex sample mixtures, are of utmost importance. [more]

Catalysis at interfaces: Atom-efficient metal catalysts based on single atoms, clusters, and nanoparticles

CatLab Lectures 2023/2024
[more]

Ultrafast Dynamics in a Photo-induced Symmetry-breaking Transition

The study of the suppression of an order parameter by an external perturbation and the following recovery of the broken-symmetry phase is a problem relevant to systems even beyond condensed matter physics. In the context of pump-probe experiments, it has been tackled considering the suppression of the charge density wave order parameter in several compounds, and it was found a relevant role played by the fluctuations [1,2]. [more]

Following the Dynamics of Nanoparticle Surfaces in Search of New Catalytic Pathways

Understanding mechanisms of work for a wide range of applied nanomaterials begins with identifying “active units” in operating conditions, zooming in on the “active sites” and ends with a model explaining their role for functioning of the material or device. [more]

Magnetic characterisation of catalysts for energy applications

CatLab Lectures 2023/2024
[more]

Wet-chemical synthesis and catalytic properties of metal clusters of small atomicity without protecting ligands

[more]

Theory of Photo- and Electro-luminescence in Scanning Tunneling Microscopy

I will talk about the theoretical perspective on a microscopy technique that combines the atomic-scale resolution of a scanning-tunneling microscope (STM) with optics. [more]

Uncovering electrocatalysts and electrochemical interfaces in situ at the nanoscale

CatLab Lectures 2023/2024
[more]

Diatomic Molecules: from hot to ultracold

In this talk I will be discussing a new ultracold molecules experiment that I'm setting up at Durham University. Ultracold molecules offer possibilities for a range of applications from controlled chemistry and testing beyond standard model physics, to quantum simulation. In this talk I will focus on what makes cold molecules promising candidates for these applications, and how we are working towards harnessing power this experimentally. [more]

Catalyst for Acetylene Hydrogenation - CatLab Approach

CatLab Lectures 2023/2024
The focus will be the catalyst characterization and development in heterogenous catalysis in particular in acetylene hydrogenation. The role of acetylene hydrogenation in industry and future renewable energy approaches will be discussed. [more]

High-power Ultrafast Moves into the Terahertz Domain

Terahertz Time Domain Spectroscopy (THz-TDS) has become a ubiquitous tool in many scientific fields and is also increasingly deployed in industrial settings. While these systems become more and more mature, efficient and lab-based THz generation methods combining broad bandwidth and high dynamic range (e.g., as provided by high THz average power and correspondingly high repetition rate) remain rare. [more]

Will a single two-level atom simultaneously scatter two photons?

The interaction of light with a single two-level emitter is the most fundamental process in quantum optics, and is key to many quantum applications. [more]

Multiscale Studies and Engineering of Surface-Reactive Systems

CatLab Lectures 2023/2024
Tomorrow’s chemicals are facing massive transitions due to the need for an alternative energy input, changing feedstock, limited resources, varying cost structures, etc. Chemical and reaction engineering is in charge for chemical and electrochemical reactions to meet the upcoming business and technical objectives. For simultaneous process-product design, a multiscale understanding provides opportunities to consider phenomena on different time and length scales of the reaction system. [more]

Non-equilibrium dynamics of laser-excited electrons in a metal

Femtosecond laser pulses irradiating a solid material induce a cascade of processes starting with the excitation of so-called hot electrons and passing through various relaxation processes. Several scattering mechanisms act on different timescales. At sufficiently high energy densities, phase transitions and ultrafast structural dynamics can be induced.We simulate the dynamics of a large ensemble of excited electrons using complete Boltzmann collision integrals. We consider the excitation of conduction electrons in a metal with visible light. On a femtosecond timescale, the electrons' energy distribution deviates strongly from a Fermi distribution. We extract spectral electron densities within specificenergy windows, and find complex behavior that cannot be matched with a single relaxation time.We show that electron-electron and electron-phonon scattering mutually influence each other during thermalization. For materials with several electronic systems, e.g. itinerant ferromagnets or dielectrics, we observe that temperatures and partial densities can be independent quantitieson picosecond timescales. [more]

Towards the Accurate Simulation of Electrochemical Interfaces by Combining Electron Density and Long-Range Machine-Learning Methods

The accurate study of electrochemical interfaces calls for simulation techniques that can treat the electronic response of metal electrodes under electrostatic perturbations. Despite recent advancements in atomistic machine-learning (ML) methods applied to electronic-structure properties, predicting the non-local behavior of the charge density in electronic conductors remains a majoropen challenge. [more]

Towards atomic diffraction through single-layer graphene

Using hydrogen atoms with a velocity of up to 120 000 m/s, we predict a high probability of coherently diffracting atoms through the natural lattice of the crystalline gratings. [more]

Recent insights on the generation, transport, and separation of charge carriers in metal oxide photocatalysts

CatLab Lectures 2023/2024
Metal oxide photoelectrodes tend to be cheap, easy to fabricate, and show relatively good (photo)chemical stability in aqueous solutions. This makes them attractive candidates as light absorbers in a variety of photoelectrochemical and photocatalytic applications. However, the energy conversion efficiencies of these absorbers are poor compared to photovoltaic-grade materials. [more]

Self-Interaction of Polarons Addressed through the Piecewise Linearity Condition

The piecewise linearity condition is a property satisfied by the exact density functional and has been found to yield band gaps in accord with experiment [1,2] when imposed to hybrid functionals. [more]

Advances in Operando Spectroscopy and Microscopy of Heterogeneous Catalysts to Make the Fuels, Chemicals and Materials of the Future

[more]

Manoeuvring chemical reactions one degree of freedom at a time

The combined use of electric fields, magnetic fields and laser light affords us an ever-increasing level of control over the properties of atoms and molecules, enabling reactivity to be probed as a function of their various degrees of freedom1. Here, we discuss how electrostatic deflection2,3 can be employed to disentangle the reactivity of molecules in different rotational states4, or with different spatial orientation of their constituent atoms5. [more]

Workshop on “THz and SFG spectroscopy and related phenomena in Solid-State Physics and Surface Science"

[more]

Workshop on “THz and SFG spectroscopy and related phenomena in Solid-State Physics and Surface Science"

[more]

Investigating supercooled water with laser- and X-ray spectroscopy

Water exhibits a variety of anomalies, some of which are particularly pronounced in the supercooled region. Its specific properties and possible structural and dynamical origins have been extensively studied, leading to the still inconclusive theory that water may exist in two structural motifs at low temperatures. [more]

Embedded Cluster Models and Solvation for the Simulation of Electrocatalysis

Heterogeneous electrocatalytic processes are notoriously difficult to simulate due to i) the complex structure of the catalyst and the electric double layer, ii) the applied bias potential that drives the reaction and iii) the variety of length and time scales on which relevant transformations happen. Accurate atomistic simulations must therefore be able to explore the configurational space of the catalyst surface – which requires fast electronic-structure methods – and enable the calculation of accurate free energies and reaction kinetics – which requires accurate electronic-structure methods. [more]

Controlling and Observing Coherent Phonons in Thin van der Waals Materials

Ultrashort laser pulses can induce coherent phonons, where all atoms in the crystal oscillate in phase. Using ultrafast electron diffraction, we can directly image this joint atomic motion in the time domain. [more]

Quantum sensors on Earth and in space

The development of quantum sensors has been one of the most important – and arguably currently most advanced – pillars of the ongoing efforts toutilize quantum technologies for practical applications. [more]

Girls´ Day

Die Kolleg*innen am Fritz-Haber-Institut haben sich einen aufregenden und abwechslungsreichen Tag einfallen lassen. / The colleagues at the Fritz Haber Institute have come up with an exciting and eventful day. [more]

Quantum Science and Technologies using Ultracold Molecules

Ultracold molecules have a wide range of applications in quantum science and technologies spanning from fundamental physics to quantum computing and quantum chemistry, and this has sparked great interest in laser cooling of molecules. [more]

"Hot" Carriers in Nanostructures – When they matter, and when they do not...

In the last couple of decades, non-thermal (“hot”) carriers in nanostructures have been simultaneously an inspirational concept to which a series of effects were ascribed, but also a source of confusion and hot debates. My talk will be aimed at describing the advances we obtained in the understanding of the role played by “hot” carriers in metals as well as transparent oxides via rigorous modelling of their generation process and dynamics, and extensive comparison to previous and new collaborative experimental work. [more]

Quantum Sensors in Diamond for Nano- and Microscale Magnetic Resonance Applications

Nitrogen vacancy (NV) point defects in diamond have emerged as a promising platform for quantum sensing. The electronic spin state of these solid-state qubits can be optically polarised, coherently manipulated with microwave pulses, and read out via their spin-state-dependent photoluminescence. Using this optically detected magnetic resonance method, magnetic signals from a single molecules or spins can be detected. [more]

Spin Effects in Adsorbed Molecules

  • PC Department Seminar
  • Date: May 16, 2024
  • Time: 02:00 PM (Local Time Germany)
  • Speaker: Richard Berndt
  • Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel
  • Location: Building G
  • Room: 2.06
  • Host: Akitoshi Shiotari
Using low-temperature scanning tunneling microscopy and occasionally synchrotron radiation methods we investigate molecules at surfaces. The experiments along with model calculations reveal molecular spin states and electron transport properties as well as intermolecular interactions. [more]

Low energy electron emission from charge exchange of slow highly charged ions with solid surfaces

The interaction of slow ions with condensed matter leads to the emission of electrons with energies typically well below 20eV. [more]

Extracting Chemistry From Core-Level Spectroscopies: Combining Theory And Experiment

The goal of X-Ray Photoelectron Spectroscopy, XPS, and X-Ray Adsorption Near Edge Spectroscopy, XANES, is to obtain information about the chemical interactions and bonding in the compound studied. [more]

Mass spectrometry in electrocatalysis research

Understanding reaction mechanisms is the key to developing new chemical reactions. [more]

New Experimental Platforms for Molecular Polaritonics

Polaritons are hybrid light-matter states with unusual properties that arise from strong interactions between a molecular ensemble and the confined electromagnetic field of an optical cavity. [more]

Thermochemistry: It’s not boring anymore!!!

One of the important areas of application for modern high-accuracy quantum chemistry is in the calculation of molecular energetics. [more]

Chemical Discovery Assisted by Machine Learning

Chemical reactions are fundamental to drive the transformation of matter and are pivotal across diverse domains like medicine, materials science, and energy generation. [more]

Homogeneous Bose gases driven far from thermal equilibrium

Far-from-equilibrium systems are ubiquitous in nature, such as in glasses, active matter, and turbulence, but are still poorly understood when compared to the unifying description of thermodynamics for systems in thermal equilibrium. [more]

From BayBE Steps to Giant Leaps - Industrial Applications of Modern Bayesian Optimization

Bayesian optimization is an old technique revived by using machine learning models at its core. This enables a plethora of extensions that really make the technique a great match for several real world applications. We showcase several examples such as custom and chemical encodings, transfer learning and slot-based mixture modelling enabled by our open-source code BayBE (https://github.com/emdgroup/baybe). [more]

Fritz Forum - FHI History

We are pleased to welcome Bretislav Friedrich, Research Group Leader Emeritus and co-author of the book One Hundred Years at the Intersection of Chemistry and Physics: The Fritz Haber Institute of the Max Planck Society 1911-2011, as the speaker for the opening event. He will present the fascinating history of the institute. [more]

Tabletop transient NEXAFS spectroscopy with a laser-produced plasma source

Laboratory-based laser-produced plasma (lpp) soft X-ray sources achieve high brightness and stability in the EUV and XUV range. With emission energies beyond 1.6 keV and stable operating times in the range of hours, they already offer numerous experimental possibilities that are independent and supplemental to investigations at large scale facilities. [more]

Ultrafast Spectroscopy of Molecules for Renewable Energies

In dye-sensitized solar cells (DSSCs) and in photo-catalytic devices designed for hydrogen production of CO2 reduction, light triggers ultrafast molecular processes, such as electron, energy transfer or singlet fission. Since these processes are at the heart of the function of the devices and of their efficiencies, the design of new molecular photo-sensitizers or catalysts can be optimized rationally if these processes are monitored by ultrafast spectroscopy. [more]

Exploring and Manipulating Materials with Ultrafast Linear and Nonlinear Scattering and Spectroscopy Techniques

Our group specializes in ultrafast spectroscopic methods, enabling in-depth studies of material chemistry in intricate environments and the control of quantum phenomena on femtosecond timescales. In the first part of this seminar, I will discuss the role of lithium in various systems from its contribution to symmetry breaking (LiNbO3), to an exotic quantum material (polar metal LiOsO3), to unravel the reasons behind the low hopping rate of lithium ions at the surface of a solid-state electrolyte (LixLa(2-x)/3TiO3). All these systems share the common feature that Li occupies a symmetry-broken state which we can selectively probe using extreme-ultraviolet second-harmonic generation spectroscopy (XUV-SHG), a novel spectroscopy pioneered in my group. In the second part I will discuss recent results on 1T-TiSe2, a prototypical charge-density-wave (CDW) compound that also exhibits strong excitonic correlations in its low-temperature phase. [more]

Lange Nacht der Wissenschaften

Wir freuen uns, ankündigen zu können, dass das Fritz-Haber-Institut an der Langen Nacht der Wissenschaften am 22. Juni 2024 teilnehmen wird. / We are excited to announce that the Fritz Haber Institute will be participating in the Long Night of Science on June 22, 2024. [more]

Brain States and the Mystery of Cognition: Using magnetic resonance imaging (MRI) to map the brain

Patterns of neural activity distributed across the brain are termed “brain states”. [more]

Ultrafast Coherent Manipulation of Free Electrons via Quantum Interaction Withshaped Optical Fields for Advanced Imaging Approaches

  • PC Special Seminar & Hybrid
  • Date: Jun 26, 2024
  • Time: 11:00 AM (Local Time Germany)
  • Speaker: Giovanni Maria Vanacore
  • Laboratory of Ultrafast Microscopy for Nanoscale Dynamics (LUMiNaD), Department of Materials Science, University of Milano-Bicocca
  • Location: Haber-Villa
  • Host: Ralph Ernstorfer
The interaction between light and electrons can be exploited for generating radiation, or for controlling electron beams for dynamical investigation of materials, enabling new applications in quantum technologies and microscopy. [more]

Live-Ptychography: How to Solve a Quantitative Live Object Transfer Function in Microscopy?

In transmission electron microscopy we record the intensity of an electron wave that has been created by the illumination optics, transmitted through a thin specimen, and then projected onto a detector. From that recorded intensity we want to learn about the specimen. [more]

Insights into Scientific Publishing

Publishing your work in an influential journal begins with good research, but there is much more to it. This interactive talk aims to demystify the editorial process from the perspective of an editor at a Nature Portfolio journal. [more]

Elucidation and Control of Advanced Photofunctions based on Excited States in Molecular Materials

Microscopic understanding of exciton physics in molecular materials for optoelectronics is a great challenge because of their complexity resulting from strong electron-phonon coupling and perhaps interaction to spin degree of freedom, electron spin-flip of intersystem crossing in molecular optoelectronic materials are strongly connected to molecular geometries in the excited states and vibronic coupling, and singlet fission, ultrafast generation of a correlated triplet pair state from a singlet excited state, is viewed as an extreme example of a concerted process of electron-phonon-spin degrees of freedom. [more]

Enhanced reactivity and selectivity of oxide-supported single atom catalysts: it is all in the local atomic environment!

Singly dispersed transition metal atoms on oxide surfaces, the so-called single atom catalyst (SAC) have recently been shown to attain chemical activity and selectivity for several technologically important reactions that surpass those of Pt single crystal surfaces, the prototype exemplary catalyst but with a large price tag. Apart from being cost-effective, single atom catalyst offer excellent opportunities for tuning their local environment and thereby their oxidation state, local coordination, and electronic structure. In this talk, I will present results of collaborative work with several experimental groups on transition metal atoms anchored on surfaces, with and without ligands, that have the potential to be cost-effective catalysts with high activity and product selectivity. [more]

Redox Flow Batteries: Navigating an Emerging Design Space

[more]

Quantum mixtures of atoms and ions: road to ultracold

Ultracold atoms and trapped ions are among the most formidable sources of coherent matter available in a laboratory. In a hybrid quantum system of atoms and ions, ultracold atoms and trapped ions are combined in a single experimental apparatus, thus realizing an innovative platform to experimentally investigate open problems of quantum physics from a new standpoint. [more]

Sommerfest | Summer Party

Die Abteilung Molekülphysik (MP) freut sich, Euch alle zum diesjährigen FHI-Sommerfest einzuladen! | The Molecular Physics (MP) department is delighted to invite you all to this years summer party! [more]

Machine Learning for First Principles Observables

CECAM Flagship Workshop
The countdown has begun for the upcoming CECAM Flagship Workshop: "Machine Learning for First Principles Observables", which will take place from the 8th to the 12th of June at the Zuse Institute, Takustraße 7, 14195, Berlin. The workshop is organized by members of the Institute´s Theory Department and further supported by CECAM, Psi-K, and DFG. [more]

Special Seminar - The Future Role of PP&B @ FHI

Science faces the challenge of ever-increasing and more complex data that push existing evaluation methods to their limits. Additional requirements such as reproducibility, data security, consistency, transferability, and reusability cause significant effort and are hardly met by traditional manual workflows. [more]

About thermionic electron emission and associative ionization

[more]

Across Molecular Timescales: Path Reweighting, Markov State Models and Machine Learning

With machine-learnt molecular potential energy functions, most notably neural-network potentials, one can now sample chemical reactions and the influence of the environment on these reactions, as well as processes at high temperature and pressure at which the approximations of empirical molecular potentials break down. [more]

Big data, small data, complex data, more data, metadata − Tackling current and future challenges of scientific IT

Science faces the challenge of ever-increasing and more complex data that push existing evaluation methods to their limits. Additional requirements such as reproducibility, data security, consistency, transferability, and reusability cause significant effort and are hardly met by traditional manual workflows. [more]

Dynamics of CO2 activation by transition metal ions - The importance of intersystem crossing

Understanding chemistry at the level of a reactive collision, that is how atoms rearrange during the reactive event, is a fundamental question in chemistry as well as in physics. [more]

Infrared Free-Electron Lasers: The State of the Art 2024

IR-FEL Symposium
A symposium entitled "Infrared Free-Electron Lasers: The State of the Art 2024" will bring together machine scientists and users of IR FELs to celebrate 10 years of the FHI FEL Facility as well as the successful commissioning of the 2-color FHI FEL Upgrade. It will take place from July 28th to 31st, 2024 in the Harnack Haus next to the FHI campus in Berlin, Germany, see https://indico.fhi-berlin.mpg.de/event/140/ [more]

2nd Gerischer Electrochemistry Today Symposium "Semiconductor Electrochemistry: From Gerischer to Lewerenz and Beyond”

This symposium honors the scientific legacies of Heinz Gerischer and Hans-Joachim Lewerenz, who contributed to the fundamental understanding of semiconductor electrochemistry, photoelectrochemical solar cells, and fuel generating systems. The meeting will bring together approximately 100 chemists, physicists, engineers, and materials scientists who are interested in the materials, processes, and interfaces in (photo)electrochemical solar energy conversion systems. [more]

Challenges on the Renewable Energy Storage

With the aim of enabling vital exchange of emerging expertise, the international conference “Challenges on Renewable Energy Storage” was set up. Following last year´s first gathering of this kind, the meeting will continue to bring together front runners of the fields catalysis and electrocatalysis, allowing them to exchange views on the most recent advancements, as well as to renew the necessary interdisciplinary networks. [more]

Systems Metrology at ZEISS Semiconductor Manufacturing Technology

Precise optics produced by ZEISS Semiconductor Manufacturing Technology (SMT) are a centerpiece of ASML photolithography machines. These tools are indispensable for digitalization: over 80% of today’s microchips are manufactured on ASML wafer steppers and scanners. [more]

How Much Interfacial Electrochemistry Can Be Understood Without Orbitals?

Electronic orbitals are a foundational concept in modern approaches to interfacial electrochemistry. While they are essential in many cases, the high computational cost of finding them could hinder the proper understanding of important practical problems. [more]

Disentangling the Processes of the Metal Nanoparticle Plasmon Decay for Photocatalytic Applications

Different processes are seen as relevant for the reaction rate enhancement of chemical reactions on optically excited metal nanoparticles. Recent studies suggest that all processes that follow a plasmon excitation, excited electrons, strong local fields and heat, can be of relevance for specific reactions. [more]

Atomic-level insights in catalytic nanomaterials by in situ surface spectroscopy and microscopy

[more]

GAP/(M)ACE Developers & Users Meeting 2024

CECAM Node Workshop
The countdown has begun for the upcoming CECAM Node Workshop: "GAP/(M)ACE Developers & Users Meeting 2024", which will take place from the 17th to the 20th of September at the Institute of Computer Science of the Free University of Berlin, Takustrasse. 9, 14195, Berlin. The workshop is organized by members of the Institute´s Theory Department , Unviersity of Warwick, Aalto University, and University of Cambridge. It is further supported by CECAM, Psi-K, DFG, and Freie Universität Berlin. [more]

Missing Ions in Laboratory and Space

Molecular ions play a vital role in space because they are readily formed by the ubiquitous cosmic ray ionisation and often undergo rapid chemical reactions even at the low temperatures of the interstellar medium. [more]

Surface chemistry and catalysis of uniform Cu2O nanocrystals with well-defined shapes

[more]

Angular momentum of small molecules: quasiparticles and topology

I will present our recent findings on small molecules kicked by laser pulses. First, I will describe a technique that allows to probe highly excited molecular states in the presence of an environment, such as superfluid 4He, and a corresponding theory based on angulon quasiparticles that is capable of describing such states, in good agreement with experiment. [more]

Modeling Strain and Moiré Effects in Large-Scale Reconstructions

Large-scale reconstructions, nanostructures, defects and moire patterns typically entail length scales of several nanometers. Their ab-initio modeling thus requires unit cells with a prohibitively large number of atoms. For example, the unit cell of magic-angle bilayer graphene, featuring superconducting many-body states, includes around 12 000 carbon atoms. [more]

Fe-doped Co3O4(111) spinel oxide epitaxial thin films for OER

[more]

IMPRS Block Course

This in-person block course of the International Max Planck Research School for ElementaryProcesses in Physical Chemistry showcases the current research within the School, exemplified by research-focus lectures from all groups involved in the IMPRS. The topics range from ultrafast surface science via catalysis to machine learning. [more]

Using Gradients in Structural Disorder to Refine Our Understanding of Electrocatalysts

[more]

Development of an Ultrafast Scanning Tunnelling Microscope Driven by Near-infrared Laser Pulses

Proteins are the machinery of life ­and understanding their structure provides important clues about their mode of action. Since proteins are so important for biology and medicine, more than 100.000 protein structures have been determined experimentally and are available in databases. [more]

Fritz Forum - Genes and Peoples

Our neighbors from the Max Planck Institute for Molecular Genetics, Sándor Fülöp and Dr. Jakob Schweizer, will be giving a talk on “Genes and Peoples: Research & Life at the Max Planck Institute for Molecular Genetics”. [more]

Hydrogen/Deuterium 1S-3S spectroscopy and beyond

In this talk, I would like to present our latest result on the 1S-3S two-photon continuous wave spectroscopy of Deuterium atoms. [more]

Workshop on Workplace Communication for Women in Science

The workshop offered a great opportunity for participants to find their own voice and experiment with various communication strategies. [more]

From BIG-Data to HOT-Extreme-Properties of High-Entropy Carbides, Carbo-Nitrides and Borides

The need for improved functionalities in extreme environments is fueling interest in high-entropy ceramics. [more]

Record Stability and Accuracy in a Strontium Optical Clock

Atomic clocks have revolutionized precision measurement. Each advancement in timekeeping, from pendulum clocks to quartz oscillators, from microwave atomic clocks to optical atomic clocks, opens the door to new areas of physics. [more]

Ordered organic monolayers on silicon

[more]

An introduction to resonant nonlinear optical frequency conversion

Direct single-mode cw laser sources cover a broad wavelength interval for an almost unimaginable range of applications. [more]

Using X-Ray Absorption Spectroscopy to Understand Thin Film Electrocatalysts

CatLab Lectures 2024/25
The combination of electrochemical methods (EC) and X-ray absorption spectroscopy (XAS) is a powerful approach to understand electrocatalysis on an atomistic level. While electrochemistry registers electrons that are passed through the external circuit, the element-specific XAS can pinpoint the source or sink of these electrons, i.e. identify the electrochemically active element or elements under and given condition. [more]

BERLIN SCIENCE WEEK - Berlin Postdoc Day 2024

Berlin PostDoc Day 2024 (Nov 7-8) is an event for postdocs and PhD students to network, share research, and explore career paths through talks and workshops. [more]

Ionization-induced dynamics in water and aqueous solutions uncovered via ultrafast time-resolved x-ray absorption spectroscopy and theoretical modeling

Our understanding of the immediate response of matter to ionization is crucial for many fields. [more]

Fundamentals and Operando Insights into Electrochemical Solid-Liquid Interfaces

CatLab Lectures 2024/25
Electrocatalysis represents one of the key technologies in facilitating the energy transition, particularly in the context of electrifying pivotal processes within the chemical energy sector. The combination of renewable power sources with electrolysis allows for the clean and decentralized conversion of electrical energy into chemical energy stored, for example, in hydrogen-related bonds. [more]

Molecules and Materials in Conversation: Encoding and Decoding Chemistry with Language Models

CatLab Lectures 2024/25
The field of chemical sciences has seen significant advancements with the use of data-driven techniques, particularly with large datasets structured in tabular form. However, collecting data in this format is often challenging in practical chemistry, and text-based records are more commonly used. [more]

Joint FHI-ICAT Symposium

The Symposium will present an opportunity to exchange expertise and engage in stimulating discussion on the subject of catalysis and its recent advancements.

Tracking Disorder and heterogeneity in ultrafast phasetransitions

Driving phase transitions in materials with light on the ultrafast enables rapid control over material properties. Ultrafast spectroscopies have advanced so that we can track these events with attosecond temporal resolution. However, in general, time-resolved measurements are spatially averaged, so we do not know what is happening spatially. In (or close to) equilibrium, we know that phase transitions are often heterogeneous, with both phases existing on different length scales, but currently we do not know what happens on ultrafast timescales as we lack probes that can measure in time and space. In this talk, I will present our work where we exploit the power of X-ray lasers (XFELs) to study light-induced phase transitions on a range of length scales. I will show how we can track and control how the distribution of atomic positions changes during the phase transition. How we can use X-rays to measure phase transitions at a surface of a crystal, and how we can use resonant soft X-rays to image dynamic heterogeneity on the nanoscale. [more]

Para-ortho H2 conversion by collisions with O2 and NO

It has been known since 1927 that two modifications of hydrogen exist: para-H2 and ortho-H2. Pure para-H2 can be prepared by leading a 1:3 para:ortho mixture of “normal” H2 over a catalyst at low temperature. In 1933 Farkas and Sachsse [1] measured the rate coefficient of para-ortho H2 conversion in gas mixtures with the paramagnetic open-shell molecules O2, NO, and NO2. [more]

Resonant Photoelectron Spectroscopy from Liquids and Solid-liquid Interfaces

CatLab Lectures 2024/25
I will present recent research topics my group and I have been working on at the Helmholtz- Zentrum Berlin, where we spectroscopically investigate the electronic structure of liquids and solid–liquid interfaces; in particular, metal-oxide nanoparticle–water interfaces using liquid microjets, and electrolyte–anode interfaces using micro-fluidic (photo-)electrochemical cells. [more]

Helium atom and helium-like ions - where are we today?

The Z-Helium atom is Nature's simplest atomic, 3-body system. [more]

Electron and Phonon Transport for Bulk Thermoelectrics, From High-Throughput Screening, Machine Learning Potential, to Electron-Phonon Renormalization

The basic transport properties of thermoelectrics (TEs) are governed by electron and phonon, as well as their interaction. The transport properties have been well-documented for more than half century. [more]

Broken Patterns - Anomalies in the Spectra of Aluminum Monofluoride

Usually, rotational spectra of diatomics can be described by a handful of spectroscopic parameters. [more]

Synthetic Materials Chemistry for a Green Hydrogen Future and Beyond

CatLab Lectures 2024/25
The transition to a sustainable energy future relies on developing efficient and scalable methods for green hydrogen production, a fundamental factor for decarbonizing energy and chemical industries. Electrocatalysis plays a pivotal role by enabling efficient cathodic hydrogen evolution and anodic oxygen evolution reaction. [more]

Electrochemical SERS Measurement Revealed Interfacial Molecular States During Dynamic Changes in the 2D Diffusion and Chemical Reaction

Liquid-Solid interfaces are the primary region where molecules interact through molecular motion and chemical reactions. However, it is challenging to gain insight into how interactions between the surface and solution modify molecular behavior. A powerful tool for evaluating these phenomena and molecular properties is in-situ surface-sensitive vibrational spectroscopy, such as surface-enhanced Raman scattering (SERS) induced by plasmonic materials.[1] [more]

Dynamics of Water/Metal Interface for Aqueous-Phase Hydrogenation

The presence of water has been shown to enhance hydrogenation of polar chemical functional groups, such as C=O and N=O bonds, through proton shuttling. To demonstrate such rather sophisticated reaction pathways, explicit solvent models with dynamic change of local solvent structures should be considered. Beyond what we reported previously for water-promoted C=O hydrogenation in furfural1, in this presentation, we will highlight how the dynamics of the local water structures within the first solvation shell may affect the hydrogenation kinetics. [more]

Sustainable Chemistry Through Tailored Catalytic Interfaces of Nanoporous Materials

CatLab Lectures 2024/25
Catalysis is a critical technology with significant importance for the economic and ecological future of our society, as it is central to the development of resource-efficient and sustainable processes for energy and material conversion. [more]

Quasiparticles formation, dynamics and free carriers in 2D TMDC structures captured by TR-µARPES and nano-ARPES

Transition metal dichalcogenides (TMDC) are excellent models for the exploration of semiconductor physics at the 2D limit, with potential applications in electronics, optoelectronics, and quantum devices. The strong Coulomb interactions and distinct structural symmetries in these materials give rise to a rich variety of photoexcited states, including excitonic complexes that are tightly bound electron-hole pairs, and valley-spin polarized. However, directly accessing the momentum direct and indirect excitons and their dynamics are out of optical experimental reach. Here, I will talk about the generation of high repetition rate higher order harmonics (HRR-HHG) and its coupling with momentum microscope, to establish HRR time- and angle -resolve photoemission spectroscopy (TR-µARPES), demonstrated on a micron-scale monolayer WSe2 flake (1). This measures the momentum direct and forbidden excitonic states across entire Brillouin Zone (BZ) and measures their dynamics under different excitation conditions (2). The direct access of excitonic energy-momentum distribution leads to the measurement of excitonic wave function revealing the exciton size in real and k-space, whose electron follows the downward curvature of its partner hole (3). Beyond excitonic states, I will also visualize the evolution of the conduction band electrons in a 1LWS2-gated device captured through nano-ARPES (4). [more]

Probing and Controlling Lattice Dynamics in Chemical Systems: from 2D Materials to Batteries

Combining lattice and electronic dynamics with functional material properties is a holy grail for condensed matter science. For example, combing semiconducting and magnetic states in a material would enable the unlocking of spin-based electronics such as non-volatile transistors, which are key for low-energy computing [1]. In this talk I will detail our efforts towards lattice-based control of material properties in two important areas. [more]

Testing the Standard Model with Molecules

Search for violation of fundamental symmetries provides a unique opportunity for testing the Standard Model. Atomic and molecular experiments offer a low energy and comparatively inexpensive alternative to high energy accelerator research in this field. [more]

Probing Local Structures and Structural Dynamics in Solid Catalysts with Electrons

CatLab Lectures 2024/25
Heterogeneous catalysis is considered one of the key technologies in prospective energy conversion scenarios. Yield, efficiency and lifetime of heterogeneous catalysts will become of utmost importance and the demand of novel high-performance catalysts fulfilling the above-mentioned criteria will rise tremendously. To cope with the prospective high demand for these functional solids, current catalyst development approaches based on empirical optimization may become insufficient and should be replaced by knowledge-based catalyst design strategies. [more]

The Advanced Research Center for NanoLithography: better chips-making-tools using fundamental physics research.

ARCNL in Amsterdam started in 2014 upon an initiative of ASML. [more]

Operando Soft X-ray Spectroscopies for Observing Reactions at Thermo- and Electrocatalytic Interfaces

Laser excitation and spectroscopy of the Thorium-229 nucleus

Among all known isotopes, Thorium-229 has the lowest nuclear excited state, only 8.4 eV above the ground state. [more]

Simulations in Electrochemical Systems

Coupled Catalytic Reactions and Key Technologies for Sustainable Chemical Production

[more]

Bridging Native and Intrinsic Structures of Microhydrated Biomolecules by Cryogenic Ion Spectroscopy

Over the years, cryogenic ion spectroscopy has established itself as a powerful technique for studying the structures and properties of biomolecules in the gas phase. [more]

Bimetallic Catalyst for Hydrogenation Reactions

CatLab Lectures 2024/25
A series of independent lectures on fundamentals and latest developments in heterogeneous catalysis, thin film technology, physical chemistry, process engineering and materials design. [more]

Nano- and microelelctroanalytic methods for understanding electrocatalysts

[more]

Fritz Forum - Mental Health

We are pleased to announce that the third edition of the Fritz Forum will feature Dipl.-Psych. Jörg Bergmann, who will give a lecture on the topic of mental health. The event will take place on January 29th at 16:30 in the FHI library and will be titled “Mental Health: A Societal and Organizational Issue”. [more]

Advanced electrochemical tools to characterise nano-electrocatalysts

[more]

Structural Dynamics of Water, Ice, and Chemical Reactions Revealed by X-ray Experiments at FELs

X-ray science has evolved dramatically with the use of X-ray free electron lasers (XFELs) that can generate ultrashort X-ray pulses with unprecedented brilliance and coherence. [more]

How to Make Fuels and Chemicals with Sunlight: Artificial Photosynthesis

CatLab Lectures 2024/25
Artificial photosynthesis offers a transformative approach to sustainable fuel and chemical production by mimicking natural photosynthesis to convert sunlight, CO₂, and water into value-added products. This presentation highlights recent progress in developing advanced photoelectrodes and tailoring catalytic microenvironments to enhance reaction efficiency and selectivity. [more]

Spectroscopic investigation of proton bonding at sub-kelvin temperatures

The proton bond is a pivotal chemical motif with significant implications across science and technology, yet its quantum chemical description is challenged by nuclear and charge delocalization effects. [more]

The Many Roles of Nanostructured Carbon Materials in Heterogeneous Catalysis

CatLab Lectures 2024/25
Nanostructured carbon materials are a fascinating class of materials to showcase possible synergies and to develop novel, disruptive concepts for heterogeneous catalysis at the border between materials chemistry research and catalysis research. [more]

Catalysts of Change: Advanced Materials Steering Health and Energy Transition

CatLab Lectures 2024/25
Advanced materials are driving innovation across all fields of technology, ranging from construction and mechanical engineering, automotive and electromobility, to medical technology, energy storage and conversion technologies, and microelectronics. [more]

Progress in laser cooling the AlF molecule

The aluminium monofluoride molecule (AlF) is a promising candidate for laser cooling and trapping at high densities. [more]

Deciphering the Structure of Single Active Sites Under In Situ and Operando Conditions Using X-ray Absorption Spectroscopy

CatLab Lectures 2024/25
Understanding the structure of catalysts under relevant reaction conditions is crucial, as their active sites often undergo dynamic changes. These transformations can significantly influence the catalytic performance, emphasizing the importance of employing operando techniques that enable real-time monitoring. This seminar will explore the application of X-ray Absorption Spectroscopy (XAS) to identify spectral signatures and molecular structures of active sites under in situ and operando conditions. XAS is particularly advantageous for such studies due to its chemical selectivity and sensitivity to the local atomic environment, offering fundamental insights into the electronic and structural properties of the investigated materials. [more]

Emerging Oxide and Nitride Semiconductors for Solar Energy Capture and Conversion

Transition metal oxide and nitride semiconductors offer considerable promise for a range of applications, from sustainable (opto)electronics to photocatalytic energy conversion. However, such materials are characterized by complex carrier-lattice couplings, defect properties, and chemical susceptibilities that must be characterized and controlled to enable their implementation in functional systems. [more]

Chirality and the electron spin- A miraculous match

Spin based properties, applications, and devices are commonly related to magnetic effects and to magnetic materials. [more]

Photoelectron and fluorescence spectroscopy of cryogenically cooled ions

Cryogenic ion traps combined with buffer gas cooling provide ideal conditions for preparing molecular ions in their vibrational ground states. [more]

Structured Illumination Compressive Hyperspectral Sum Frequency Generation Microscopy- CS-SFG

Sum frequency generation spectroscopy (SFG) is a valuable technique to study the molecular properties of surfaces. As a second-order technique, it is uniquely sensitive to the average organization of molecules at the surface. However, as most surfaces are spatially heterogeneous, it isn't easy to interpret the spectrum as a single domain. The development of SFG into microscopy has allowed a more detailed and accurate analysis of the spatio-spectro-temporal evolution of surface chemistry. The SFG microscope development will be presented, and compressive sensing and the application toward thin films will be used. [more]

Robots and the Search for Universal Intelligence: How Machines Learn to Move, Think, and Adapt

[more]

PP&B Workshop - Experimental Control with EPICS and the Scientific Computing Infrastructure at FHI

Both days include an introductory morning session (10:00-12:00) and a hands-on afternoon session (14:00-16:00). While the first day (Tuesday) covers topics related to Experimental Control via EPICS, the second day (Wednesday) will focus on the FHI Compute Infrastructure and the Viper Supercomputer. [more]

Designing 2D Molecular Quantum Spin Array on Solid Surfaces

We aim to control the symmetry of molecular spin structures on solid surfaces and design a two-dimensional (2D) organic quantum bit network with exceptional quantum spin properties. To achieve this, we have employed transition metal atoms and organic molecules as materials. Over the past two decades, we have investigated surface spin structures using scanning tunneling microscopy and spectroscopy (STM/STS), as well as spin-polarized STM/STS, all conducted in ultrahigh vacuum (UHV) at cryogenic temperatures, in combination with density functional theory (DFT) calculations [1-4]. [more]

Prediction of Deep Core-Level Spectra of Large Systems with GW and Beyond

While the GW method is well-established for calculating valence photoemission spectra of solids and molecules [1], its application to deep core levels with excitation energies exceeding 100 eV is a more recent advancement. [more]

Matter-wave interferometry from electrons to nanoparticles - recent ideas and applications

Modern matter-wave experiments cover a broad mass range from single electrons to molecules consisting of hundreds of atoms. Levitated optomechanics promises to be-come a platform for matter waves of nanoparticles weighing a billion atomic mass units. [more]

Deciphering spectral signatures of proton delocalization in complexes of hydroxide and hydronium ions with water molecules

One class of system where explorations of larger complexes is particularly instructive involves complexes of ions with water molecules. In these systems the cooperative nature of the hydrogen bond that are formed leads to large changes in the strengths of the ion-water interactions as more water molecules are introduced, and this, in turn, has a large effect on the spectroscopy. [more]

Girls´Day 2025

Die Kolleg*innen am Fritz-Haber-Institut haben sich einen aufregenden und abwechslungsreichen Tag einfallen lassen. / The colleagues at the Fritz Haber Institute have come up with an exciting and eventful day. Anmeldung ab 17.02.2025 [more]

Functional Ceramics – Future Strategies for Modifying Properties and Enabling Fast Sintering

The functional properties of ceramics are usually tailored by designing point defects and interfaces. Dislocations as heavily charged nanoscale one-dimensional line defects are so far underrepresented means to tune functionality. However, the opportunity to tune ceramics beyond what can be achieved by chemical doping is of significant interest. [more]

Photoelectron Circulardichroism in the Photodetachment of Electrosprayed Anions

Research aiming at the quantification of molecular chirality by chiroptical techniques continues to attract a significant amount of interest in chemistry, physics, biology and pharmacology. [more]

Accurate and Transferable DFT: Machine-Learned aPBE0 and Physics-Based XDM in FHI-Aims

I present the implementation and application of the accurate, machine-learned aPBE0 functional and the exchange-hole dipole moment (XDM) dispersion correction within the FHI-aims code. [more]

Guiding Experiments in Materials Science Using Information Driven Approaches Based on Data as well as Theory

My aim is to show how data, as well as physics based models, can be utilized in conjunction with data science to guide materials discovery. [more]

Uncertainty-Aware Exploration of Atomic Energy Landscapes

Atomic simulations allow fantastic insight for chemistry and materials science, but in silico data has many uncertainties which complicate interpretation and prediction. I will discuss recent Bayesian methods to quantify two important sources of uncertainty: those arising from imperfect models for atomic interaction[1,2] and incomplete sampling of the atomic energy landscape[3]. [more]

MP Department Seminar by Dr. Karl Horn

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TH-Seminar: Dr. Matthias M. May

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Hitler's Atomic Bomb

After the discovery of nuclear fission, scientists in several different countries, including National Socialist Germany, brought the potential military applications of fission to the attention of political and military authorities. [more]

CECAM Flagship Workshop: From operando electron microscopy images to atomistic models: Machine Learning assisted analysis in the age of big data

The advent of in situ and operando analytical techniques in material science has allowed uncovering the importance of structural dynamics in research fields such as heterogeneous catalysis [1], nucleation and growth of crystals [2] or proteins [3]. This holds, in particular for electron microscopy related operando approaches, true to the slogan: “seeing is believing" [4]. [more]

TH-Seminar: Prof. Lars Borchardt

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Challenges on the Renewable Energy Storage

With the aim of enabling vital exchange of emerging expertise, the international conference “Challenges on Renewable Energy Storage” was set up. Following the first two gatherings of this kind in 2022 and 2024, the meeting will continue to bring together front runners of the fields catalysis and electrocatalysis, allowing them to exchange views on the most recent advancements, as well as to renew the necessary interdisciplinary networks. [more]
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