Cold and ultracold chemistry

The chemical and physical process involving charged and neutral particles with internal degrees of freedom

Atom-ion quantum hybrid systems

A molecular ion immersed on an ultracold gas.

The development of hybrid trap technologies for simultaneous cooling and trapping of atoms and ions has brought about the possibility of studying chemical reactions between charged and neutral particles with significant control over the internal states of the collisional partners. This hybrid technology is appropriate to study ion-neutral collisional processes down to temperatures of a few mK. Only recently the field has evolved towards the study of molecular ion-neutral collisions.

In our group, we study vibrational and rotational relaxation of molecular ions in the presence of a buffer gas or ultracold atomic gas. As a few-body oriented group, we also study ion-atom-atom three-body recombination, which turns out to be the dominant reactive channel of an ion is immersed in a high-density ultracold gas. In most of these applications, although, at cold temperatures, many partial waves play a role in the scattering owing to the strong charge-neutral long-range interaction. These problems are treated mainly from a classical approach owing to a large number of partial waves present at cold temperatures for ion-neutral systems.

Rydberg physics

Potential energy curves relevant for chemi-ionization, which is one of the main decay mechanisms of an ultra-long-range Rydberg molecule.

Rydberg physics is a classic in the atomic community. Surprisingly enough, still, it is a theme in vogue, owing to the promising applications of Rydberg atoms in quantum information systems and the recent observations of ultra-long-range Rydberg molecules. Ultra-long-Rydberg molecules appear when a Rydberg atom is immersed in a high-density ultracold gas, generally a Bose-Einstein condensate. These molecules are studied from a many-body physics approach or an atomic physics approach. However, in general, in any of these approaches, the stability of these molecules is studied. In our group, we investigate the different chemical processes that induce the decay of these molecules and hence define the lifetime of such exotic molecular bound. 

Laser cooling of molecules and ultracold chemistry

Laser cooling scheme for AlF

Laser cooling of atoms has revolutionized the field of atomic, molecular, and optical physics in the last decades. This technique provides the playground for a lot of intriguing phenomena, such as the Bose-Einstein condensation or quantum information. However, despite its success with atoms, it has been only recently when it has been applied to molecules.

In our group, we perform ab initio quantum chemistry calculations, and at the same time, we apply inversion techniques to get accurate potential curves from spectroscopic data. Within this approach, it is possible to identify realistically robust candidates for laser cooling of molecules.

The study of cold and ultracold processes for atom-molecule and molecule-molecule collisions is another of our interests. In particular, we are passionate about the chemistry in a buffer gas source after the ablation of a given target and about the rovibrational energy transfer for molecule-molecule collisions at ultracold temperatures. 

Photo-association reaction controlled via light-matter interaction by means of the photonic band structure provided by a photonic crystal.

The general interest in the ultimate control of light-matter interaction at the single-photon level has fueled the development of photonic materials. These devices enable the strong coupling between photons and atoms employing the guided modes of the material. This new paradigm offers a unique scenario for the study of scalable quantum networks, light-matter quantum phases, and quantum metrology.

In our group, we are interested in exploiting the strong light-matter paradigm to manipulate and control light-assisted chemical reactions at ultracold temperatures, such as photo-association. In the same vein, we explore coherent control approaches to photo-association reactions, although, in our approach, we select the reactant states to lead to the desired product state.


Jesús Pérez-Ríos
An introduction to cold and ultracold chemistry: Atoms, Molecules, Ions and Rydbergs.
Springer Nature
Henrik Hirzler, Eleanor Trimby, Rianne S Lous, Gerrit C Groenenboom, Rene Gerritsma, Jesús Pérez-Ríos
Controlling the nature of a charged impurity in a bath of Feshbach dimers
Phys. Rev. Research 2, 033232
Maximilian Doppelbauer, Nicole Walter, Simon Hofsäss, Silvio Marx, H Christian Schewe, Sebastian Kray, Jesús Pérez-Ríos, Boris G Sartakov, Stefan Truppe and Gerard Meijer
Characterisation of the b3Σ+, ν=0 state and its interaction with the A1Π state in aluminium monofluoride
Molecular Physics e1810351
Vanessa Olaya, Jesús Pérez-Ríos, and Felipe Herrera
C6 coefficients for interacting Rydberg atoms and alkali-metal dimers
Physical Review A 101, 032705
Stefan Truppe, Silvio Marx, Sebastian Kray, Maximilian Doppelbauer, Simon Hofsäss, Hanns Christian Schewe, Nicole Walter, Jesús Pérez-Ríos, Boris G Sartakov, and Gerard Meijer
Spectroscopic characterization of aluminum monofluoride with relevance to laser cooling and trapping
Physical Review A 100, 052513
Jesús Pérez Ríos
Vibrational quenching and reactive processes of weakly bound molecular ions colliding with atoms at cold temperatures
Physical Review A 99, 022707
Jesús Pérez Ríos and Chris H. Greene
Universal temperature dependence of the ion-neutral-neutral three-body recombination rate
Phys. Rev. A 98, 062707
David B. Blasing, Jesús Pérez-Ríos, Yangqian Yan, Sourav Dutta, Chuan-Hsun Li, Qi Zhou, and Yong P. Chen
Observation of Quantum Interference and Coherent Control in a Photochemical Reaction
Phys. Rev. Lett. 121, 073202
J. D. Whalen, F. Camargo, R. Ding, T. C. Killian, F. B. Dunning, J. Pérez-Ríos, S. Yoshida, and J. Burgdörfer
Lifetimes of ultralong-range strontium Rydberg molecules in a dense Bose-Einstein condensate
Phys. Rev. A 96, 042702
Chris H. Greene, P. Giannakeas, and J. Pérez-Ríos
Universal few-body physics and cluster formation
Rev. Mod. Phys. 89, 035006
B. C. Yang, Jesús Pérez-Ríos, and F. Robicheaux
Classical fractals and quantum chaos in ultracold dipolar collisions
Phys. Rev. Lett. 118, 1154101
Jesús Pérez-Ríos, May E. Kim and Chen-Lung Hung
Ultracold molecule assembly with photonic crystals
New J. Phys. 19, 123035
Sandra Brünken, Lars Kluge, Alexander Stoffels, Jesús Pérez-Ríos and Stephan Schlemmer
Rotational state-dependent attachment of He atoms to cold molecular ions: An action spectroscopic scheme for rotational spectroscopy
J. Mol. Spectroscopy 332, 67
Sourav Dutta, Jesús Pérez-Ríos, D. S. Elliott, and Yong P. Chen
Two-photon photoassociation spectroscopy of an ultracold heteronuclear molecule
Phys. Rev. A 95, 013405
Jesús Pérez-Ríos and F. Robicheaux
Rotational relaxation of molecular ions in a buffer gas
Phys. Rev. A 94, 032709
D. B. Blasing, I. C. Stevenson, J. Pérez-Ríos, D. S. Elliott, and Y. P. Chen
Short-range photoassociation of LiRb
Phys. Rev. A 94, 062504
Thomas Niederprüm, Oliver Thomas, Tanita Eichert, Carsten Lippe, Jesús Pérez-Ríos, Chris H. Greene and Herwig Ott
Observation of pendular butterfly Rydberg molecules
Nature Communications 7, 12820
Michael Schlagmüller, Tara Cubel Liebisch, Felix Engel, Kathrin S. Kleinbach, Fabian Böttcher, Udo Hermann, Karl M. Westphal, Anita Gaj, Robert Löw, Sebastian Hofferberth, Tilman Pfau, Jesús Pérez-Ríos, and Chris H. Greene
Ultracold Chemical Reactions of a Single Rydberg Atom in a Dense Gas
Phys. Rev. X 6, 031020
Michael Schlagmüller, Tara Cubel Liebisch, Huan Nguyen, Graham Lochead, Felix Engel, Fabian Böttcher, Karl M. Westphal, Kathrin S. Kleinbach, Robert Löw, Sebastian Hofferberth, Tilman Pfau, Jesús Pérez-Ríos, and Chris H. Greene
Probing an Electron Scattering Resonance using Rydberg Molecules within a Dense and Ultracold Gas
Phys. Rev. Lett 116, 053001
Artjom Krükow, Amir Mohammadi, Arne Härter, Johannes Hecker Denschlag, Jesús Pérez-Ríos, and Chris H. Greene
Energy Scaling of Cold Atom-Atom-Ion Three-Body Recombination
Phys. Rev. Lett 116, 193201
Jesús Pérez-Ríos, Matthew T. Eiles and Chris H. Greene
Mapping trilobite state signatures in atomic hydrogen
J. Phys. B 49, 14LT01
Matthew T. Eiles, Jesús Pérez-Ríos, F. Robicheaux and Chris H. Greene
Ultracold molecular Rydberg physics in a high density environment
J. Phys. B 49, 11405
Tara Cubel Liebisch, Michael Schlagmüller, Felix Engel, Huan Nguyen, Jonathan Balewski, Graham Lochead, Fabian Böttcher, Karl M Westphal, Kathrin S Kleinbach, Thomas Schmid, Anita Gaj, Robert Löw, Sebastian Hofferberth, Tilman Pfau, Jesús Pérez-Ríos, Chris H. Greene
Controlling Rydberg atom excitations in dense background gases
J. Phys. B 49, 182001
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