Femtosecond transparency in the extreme ultraviolet

TL;DR

This paper theoretically investigates femtosecond transparency in the extreme ultraviolet by modeling autoionizing states in helium under intense laser dressing, providing ab initio solutions that align with experimental observations.

Contribution

It introduces a rigorous ab initio method for modeling ultrafast XUV transparency involving autoionizing states with laser dressing effects.

Findings

Transient absorption spectra match experimental data

Autoionizing states are effectively modeled with TDSE

Laser dressing influences autoionization dynamics

Abstract

Electromagnetically induced transparency-like behavior in the extreme ultraviolet (XUV) is studied theoretically, including the effect of intense 800 nm laser dressing of He 2s2p (1Po) and 2p^2 (1Se) autoionizing states. We present an ab initio solution of the time-dependent Schrodinger equation (TDSE) in an LS-coupling configuration interaction basis set. The method enables a rigorous treatment of optical field ionization of these coupled autoionizing states into the N = 2 continuum in addition to N = 1. Our calculated transient absorption spectra show encouraging agreement with experiment.