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

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 {\tt tRecX-haCC} package developed by the authors. The {\tt 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.