Nuclear non-resonant photoexcitation assisted by electron recombination
Abstract
We investigate theoretically a nuclear excitation mechanism involving absorption of non-resonant photons leveraged by the coupling to the atomic shell. The nuclear non-resonant photoexcitation is assisted by electron recombination which compensates the energy mismatch between photon and nuclear transition energies, reminiscent of parametric up-conversion in non-linear media. This third-order process proceeds via a virtual nuclear state rather than virtual electronic states, distinguishing this mechanism from the electronic bridge. We investigate the process on the example of a so-far not observed 14.2 keV hard x-ray transition in 193Pt driven by an x-ray free-electron laser. Although the calculated cross section is small, it can be compensated by the vast number of non-resonant photons from the x-ray laser pulse. By enabling nuclear excitation through non-resonant photons, this up-conversion-like mechanism suggests new directions for non-linear x-ray interactions mediated by nuclear transitions.
Keywords
Cite
@article{arxiv.2604.24045,
title = {Nuclear non-resonant photoexcitation assisted by electron recombination},
author = {Nan Xue and Zuoye Liu and Ziwen Li and Adriana Pálffy and Jianmin Yuan and Yuanbin Wu and Xiangjin Kong and Yu-Gang Ma},
journal= {arXiv preprint arXiv:2604.24045},
year = {2026}
}