The IAP was founded on June 2nd, 1961 as part of the faculty of natural sciences. Today about 56 employees research and teach in four divisions focusing on Biomedical Photonics, Laser Physics, Nonlinear Optics and Microwave Physics.
Institute of Applied Physics
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Optically Controlled Electron Transfer in a Re(I) Complex
We demonstrate ultrafast optical control of intramolecular charge flow which paves the way for photocurrent modulation and switching with a highly wavelength-selective ON/OFF ratio. The system we explore is a fac-[Re(CO)3(TTF-DPPZ)Cl] complex, where TTF-DPPZ = 4’,5’-bis(propylthio)tetrathiafulvenyl [i]dipyrido [3,2-a:2’,3’-c]phenazine. DFT calculations and AC-Stark spectroscopy confirm the presence of two distinct optically active charge-transfer processes, namely a metal-to-ligand charge transfer (MLCT) and an intra-ligand charge transfer (ILCT). Ultrafast transient absorption measurements show that the ILCT state decays in the ps regime. Upon excitation to the MLCT state, only a long-lived 3MLCT state is observed after 80 ps. Remarkably, however, the bleaching of the ILCT absorption band remains as a result of the effective inhibition of the HOMO-LUMO transition.
THz-driven split ring resonator undulator
We propose a short period undulator based on the electromagnetic field pattern in a THz-driven split ring resonator structure. An analytical model is developed that allows us to assess the key performance parameters of the undulator and to estimate the emitted radiation spectrum. Different geometric configurations are compared in detail using numerical simulations. A 100 MeV electron bunch with 5 pC charge is shown to emit narrow band 83 eV photon pulses with a peak brightness of approximately1019 photons=ðs mrad2 mm2 0.1% BWÞ when passing through the 100 mm long undulator with a 1 mm period.
High-resolution phase-sensitive sum frequency generation spectroscopy by time-domain ptychography
We demonstrate that time-domain ptychography, when applied to a set of broadband vibrational sum frequency spectra, reconstructs amplitude and phase of the vibrational free induction decay from an interfacial sample with a resolution that is independent of up-converting pulse bandwidth and spectrometer resolution. These important improvements require no modifications to most standard homodyne setups, and the method is applicable to other coherent homodyne spectroscopies such as coherent anti-Stokes Raman spectroscopy and transient grating spectroscopy.
Clocking the movement of electrons inside an atom
Pioneering "self referenced streaking" approach, scientists clock Auger electrons with sub-femtosecond resolution and unlock the broader potential for attosecond time resolution at XFELs.
D.C. Haynes et al. Clocking Auger electrons. Nature Physics (2021),
https://www.nature.com/articles/s41567-020-01111-0