Speaker
Description
X-ray absorption spectroscopy (XAS) in the near-edge- and extended-edge regime is well established using synchrotron light sources and provides element specific access to the unoccupied electronic structure, symmetry of orbitals and chemical bonding. The technique has been advanced in access the ultrafast time domain by generating ultra-broadband soft x-ray continua driven by phase stable few-cycle laser pulses, allowing to achieve attosecond time resolution without the principle restriction in spectral resolution. However, even in state-of-the-art experiments the photon flux and detection efficiency limits the achievable energy resolution and signal-to-noise of difference spectra, leading to extended measuring time for delay time scans in time-resolved studies. To overcome these limitations, we are currently developing a new instrument for time-resolved XAS experiments en¬abling exceptional temporal resolution down to the few-femtosecond or atto¬second regime. By combining improved laser technology with an ad¬vanced detection concept using zone plates in the spectrometer, this setup will significantly advance the current state-of-the-art aiming at a 10 times higher photon flux with 5 times better spectral resolution.
Exploiting the high timing accuracy of the new XAS instrumentation we envision novel insights into ultrafast electron and structural dynamics of solids, in particular, at the “very early” (few femtosecond) timescale, which was so far hardly accessible e.g. by trARPES. Attosecond near-edge X-ray spectroscopy will open a novel view on strongly coupled photon-carrier-phonon systems and is applicable to various materials. In our recent collaborative work on graphite, we have demonstrated the potential to disen¬tangle complex pathways of energy con¬version between photons, carriers and phonons, and provided also surprisingly new findings on electron-phonon coupling and lattice expiations for a seemingly well-studied system like graphite [1]. The element specify of XAS will be of particular relevance for the dynamics of charge and energy transfer (e.g. in layered hetero¬structures), ultrafast phase transitions in quantum materials including Mott physics and super-conductivity, but also in studies of ions and electrons in liquids.
References
[1] T.P.H. Sidiropoulos et al., Phys. Rev. X 11, 041060 (2021).
| Abstract Number (department-wise) | PC 06 |
|---|---|
| Department | PC (Wolf) |
