Single-photon and multi-photon Fano lines for helium and neon using tRecX-haCC

TL;DR

This paper investigates the lineshapes of single- and multi-photon ionization of helium and neon atoms by ultrashort EUV radiation, focusing on the Fano $q$ parameter's sensitivity to multi-photon processes using advanced computational methods.

Contribution

The authors introduce the tRecX-haCC package that accurately models multi-photon ionization and Fano resonance lineshapes in helium and neon, demonstrating the sensitivity of the Fano $q$ parameter to photon process order.

Findings

Fano lineshapes are sensitive to multi-photon excitation order.

The tRecX-haCC package effectively computes photoelectron spectra with resonance peaks.

The study reveals the dependence of the Fano $q$ parameter on multi-photon processes.

Abstract

Single-photon and multi-photon ionization of helium and neon atoms by ultrashort extreme ultraviolet radiation is studied. The wavelength of radiation is chosen to excite a set of doubly excited states. We analyse the lineshapes arising from the presence of doubly excited states and numerically demonstrate the sensitivity of the Fano $q$ parameter to the order of multi-photon process. The computations were performed using the tRecX-haCC package developed by the authors. The tRecX-haCC package solves the time-dependent Schr\"odinger equation in the presence of a laser pulse and computes the photoelectron spectra including the narrow resonance peaks using the tSurff and iSurf techniques.