Veranstaltungen

THz spintronics is an emerging field of research that combines ultrafast optics with spintronics, leveraging the speed of lasers to study magnetic dynamics. The use of THz radiation presents an energy-efficient alternative to optical pulses as it directly targets the excitation of magnons. Conversely, magnetic processes on a picosecond timescale result in the emission of THz radiation. This work explores the topic of THz spintronics from both directions. [mehr]

With the rapid advancement of attosecond science, the intrinsic timescale of electronic dynamics in atoms, molecules and solids can now be accessed. Integrating attosecond techniques with conventional scanning tunneling microscopy (STM) has the potential to enable simultaneous ångström-attosecond resolution. Here, we present our theoretical and experimental studies on the physical dynamics of attosecond STM. [mehr]

Correlation plays a central role in emergent phenomena. Examples include, among others, quantum ground states and collective excitations. Here, I will discuss what we can learn from time-domain views of correlation in two dimensional (2D) vdW materials. In the 2D vdW magnetic semiconductor, CrSBr, excitonic transition is found to strongly couple to magnetic order [1] and this allows the easy detection of low energy (GHz-THz) magnons by visible-NIR light [2]. [mehr]

Mid-Infrared (MIR) light can interact with molecules by selectively exciting molecular vibrational modes. On one hand, in combination with photonic structures, MIR can target specific vibrational states of molecular to influence chemical reactions; on the other hand, IR spectroscopy has long been used as a molecular sensing tool. In this talk, I will discuss recent advancement in my lab, focusing on these two key topics. In the first topic, I will explain how photonic environments can modify molecular dynamics through strong light-matter coupling. This strong coupling leads to the molecular vibrational polaritons – a hybrid quasiparticle between light and matter. Using two-dimensional infrared (2D IR) spectroscopy, we have demonstrated that strong coupling to photonic environments can efficiently promote energy transfer within or between molecules, subsequently slowing down competing reaction pathways. This research provide insights into designing photonic structures to modify chemical landscapes and influence reaction pathways. In the second topic, I will present the latest development in fast-scanning vibrational sum frequency generation (VSFG) microscopy, tailored to differentiate collagen tissues in healthy and tumorous conditions. We revealed distinct spectral signatures between healthy and tumorous tissues, which arise from the coherent nature of VSFG signals – akin of a microscopic Young’s double slit experiment. VSFG’s unique power to resolve varying alignments of collagen fibrils empowers it as a distinctive label-free technique for tumor identification in the future. [mehr]