THz Structural Dynamics
THz Structural Dynamics
Research Group Sebastian Maehrlein
Research Group Sebastian Maehrlein


Welcome to the THz Structural Dynamics group …

    We, the team of the new THz structural dynamics group, are obviously fascinated about structural dynamics. Why that? Material properties and chemical reactions are fundamentally determined by the spatial arrangement of atoms, ions or molecules. If we can modulate or change this spatial structure on ultrafast time scales, we can control properties on demand or even discover new material features. For this, we generate highly intense and phase stable laser pulses in the THz and midinfrared spectral range, which enable us to coherently drive specific structural dynamics on their fundamental time and energy scales. Furthermore, we want to explore tailored lattice trajectories, which may help to steer solids into hidden states. Currently, we are focusing on phonon anharmonicities, molecular orientations in solids and dynamically disordered systems.

    Feel free to roam through our fields of research, follow us @sfmaehrlein | or contact us any time. We acknowledge additional external funding from …

    Latest news …

    New group member - Michael
    Aug 2021
    Very warm welcome to Michael Spencer, who joined our group as a PostDoc! Coming all the way from New York City, Michael brings his expertise in cavity polaritons, lasing of perovskites, and polarization resolved photoluminescence. What a catch!

    We are happy to have you with us, Michael!   

    Michael’s fun fact: Michael belongs to a unique species of scientists, perfectly fit to both urban and rural habitats.
    Part of the new the Max Planck Center
    Jul 2021
    We are excited to be part of the newly founded Max Planck-Radboud University Research Center for Infrared Free Electron Laser Spectroscopy! The Center enhances the joint research capabilities of the Max Planck Society and Radboud University (Nijmegen, NL) based on their unique Free Electron Laser instrumentation. We are proud to contribute with our complementary tabletop high-field THz/MIR lab in a joint project to seek for ultrafast, but permanent, switching of material properties via phonons. Join for a PhD position!
    New Publication - JPCL Cover
    Jun 2021
    Already 2nd cover story this year with our collaborators at Columbia University. Feifan Wang used our novel 2D-OKE technique to demonstrate how optical anisotropy and phase transitions can be tuned in alloyed CsxMA1−xPbBr3 lead halide perovskites.

    F. Wang, L. Huber, S.F. Maehrlein, and X.-Y. Zhu “Optical Anisotropy and Phase Transitions in Lead Halide Perovskites”, J. Phys. Chem. Lett. 12, 20, 5016–5022 (2021)
    Outreach – Documentary filming in our lab
    May 2021
    We are always enthusiastic to support and gain visibility for women in science. This time, we were especially proud to simultaneously support a young female filmmaker:
    Our PhD student Marie Cherasse was followed during her lab work by the director Hannah Kugel for a French documentary about independent women. The documentary will be submitted to an ARTE competition. Fingers crossed, Marie and Hannah!
    New publication - Ultrafast Kerr effect in anisotropic and dispersive media
    Mar 2021
    The interpretation of ultrafast pump-probe spectroscopy in solids can be extremely challenging or even misleading if anistropic and dispersive light propagation is overlooked. Here we joined forces with L. Huber et al. from Columbia University to give a comprehensive four-wave mixing model for these phenomena; relevant to all types of time- and polarization-resolved methods, such as OKE, MOKE and Faraday effect. With this general model, the observed features can be used to quantitatively determine the anisotropic refractive index and group index dispersion. J. Chem. Phys.: [more...]
    New publication - Two Dimensional Optical Kerr effect in Hybrid Semiconductors
    Feb 2021
    Optoelectronic devices, such as photovoltaics or light-emitting diodes, are based on the interaction of light with charges in the active material. Lead halide perovskites (LHPs) have emerged as excellent materials for optoelectronics, but mysteries remain as to how these materials interact with light. In the X.-Y. Zhu group at Columbia University, S. Maehrlein and coworkers developed a multidimensional spectroscopic method (2D-OKE) to observe the nearly instantaneous responses of LHPs to propagating light fields. This novel method has allowed us to precisely trace a nonlinear material response resulting from the mixing of different light components overtaking each other during [more...]
    Tasty JACS Cover
    Jan 2021
    What started as a joke about “Belgium waffle polarons” with the X.-Y. Zhu group at Columbia University ended up on the cover of the Journal of the American Chemical Society (JACS). Sebastian contributed to this perspective on carrier screening and large polarons in Lead Halide Perovskites during the first New York City lockdown. Don’t forget the fun in science, even when times get rough.

    Have a look at the perspective article here: F. Wang et al., J. Am. Chem. Soc., 143, 5-16 (2021).

    Big thanks to the team of X.-Y. Zhu and to Yusong Bai for his cover art. [more...]
    New group member - Max
    Aug 2020
    Recently, Maximilian Frenzel joined our team as a PhD student. We are excited to welcome him with his background in lead halide perovskites from his Master’s thesis in the Snaith group at Oxford. Max will take a deep dive into THz driven structural dynamics in lead halide perovskites and will study nonlinear phenomena in two-dimensional semiconductors.

    Herzlich willkommen, Max!

    Max’ fun fact: A royal swan protected by her majesty harshly intercepted his Oxford rowing career.
    New group member - Leona
    Jun 2020
    We are happy to have Leona Nest with us for a three-month internship. Leona will spend the summer with the THz Structural Dynamics group while learning how to generate high THz fields and how to conduct THz-pump NIR-probe experiments.

    Herzlich willkommen, Leona!

    Leona’s fun fact: Besides physics, she likes to discuss about social theory and power structures in society with you.
    Group Member - Marie
    Jun 2020
    Marie Cherasse is a group member since the start of our group. She’s working on her PhD in a collaboration project with Luca Perfetti’s group (Irradiated Solids Laboratory) at Ecole Polytechnique in Paris. Marie studies ultrafast electron and cation dynamics in hybrid lead halide perovskites via ARPES / OKE in Paris and THz control in our group, respectively.

    Bienvenue, Marie!

    Marie’s fun fact: Marie likes to play music classically, but dances quantum mechanically.