Non-resonant two-photon x-ray absorption in Cu
Abstract
We present a real-space Green's function theory and calculations of two-photon x-ray absorption (TPA). Our focus is on non-resonant K-shell TPA in metallic Cu, which has been observed experimentally at intense x-ray free electron laser (XFEL) sources. The theory is based on an independentparticle Green's function treatment of the Kramers-Heisenberg equation and an approximation for the sum over non-resonant intermediate states in terms of a static quadrupole transition operator. XFEL effects are modeled by a partially depleted d-band. This approach is shown to give results for K-shell TPA in quantitative agreement with XFEL experiment and with a Bethe-Salpeter Equation approach. We also briefly discuss many-body corrections and TPA sum-rules.
Keywords
Cite
@article{arxiv.2504.10785,
title = {Non-resonant two-photon x-ray absorption in Cu},
author = {J. J. Kas and J. J. Rehr and J. Stohr and J. Vinson},
journal= {arXiv preprint arXiv:2504.10785},
year = {2025}
}
Comments
7 pages, 4 figures