Document Type
Article
Publication Date
9-27-2022
Abstract
The interaction of intense light with matter gives rise to competing nonlinear responses that can dynamically change material properties. Prominent examples are saturable absorption (SA) and two-photon absorption (TPA), which dynamically increase and decrease the transmission of a sample depending on pulse intensity, respectively. The availability of intense soft X-ray pulses from free-electron lasers (FELs) has led to observations of SA and TPA in separate experiments, leaving open questions about the possible interplay between and relative strength of the two phenomena. Here, we systematically study both phenomena in one experiment by exposing graphite films to soft X-ray FEL pulses of varying intensity. By applying real-time electronic structure calculations, we find that for lower intensities the nonlinear contribution to the absorption is dominated by SA attributed to ground-state depletion; our model suggests that TPA becomes more dominant for larger intensities (>1014 W/cm2). Our results demonstrate an approach of general utility for interpreting FEL spectroscopies.
Recommended Citation
Hoffmann, Lars, et al. “Saturable Absorption of Free-Electron Laser Radiation by Graphite near the Carbon K-Edge.” The Journal of Physical Chemistry Letters, vol. 13, no. 39, Oct. 2022, pp. 8963–70, https://doi.org/10.1021/acs.jpclett.2c01020.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Publication Title
The Journal of Physical Chemistry Letters
DOI
10.1021/acs.jpclett.2c01020
Comments
© 2022 The Authors. Published by American Chemical Society