Schiwietz, G.; Kachel, T.; Mitzner, R.; Holldack, K.: Surface dynamics of graphite probed by soft x-ray linear dichroism in Auger-emission yield. Physical Review B 107 (2023), p. 054306/1-12
10.1103/PhysRevB.107.054306
Open Access Version
Abstract:
Time-resolved near-edge x-ray absorption with Auger-electron detection is employed as a surface-sensitive probe to study the dynamics of surface atomic motion in graphite upon laser excitation. To this end, ultrafast changes in photoelectron spectra with a focus on carbon KVV-Auger intensities are used as probe in a pump-probe scheme with pulsed femtosecond near-infrared laser excitation of a highly oriented pyrolytic graphite (HOPG) sample. The dynamics of the HOPG surface excitation at the K edge appears as transient change in Auger yield. Since the directional bond character of carbon is reflected in linear dichroism of x-ray absorption, the transient angular variation of the 1s→π transitions can be used to uncover the laser-induced dynamics of the atomic surface structure which shows a huge anisotropy upon usage of s- or p-polarized x-ray probe pulses, respectively.