Controlling the $2p$ Hole Alignment in Neon via the $2s$-$3p$ Fano Resonance

Abstract

We study the state-resolved production of neon ion after resonant photoionization of Ne via the $2s$-$3p$ Fano resonance. We find that by tuning the photon energy across the Fano resonance a surprisingly high control over the alignment of the final $2p$ hole along the polarization direction can be achieved. In this way hole alignments can be created that are otherwise very hard to achieve. The mechanism responsible for this hole alignment is the destructive interference of the direct and indirect (via the autoionizing $2s^{-1}3p$ state) ionization pathways of $2p$. By changing the photon energy the strength of the interference varies and $2p$-hole alignments with ratios up to 19:1 between $2p_0$ and $2p_{\pm 1}$ holes can be created: an effect normally only encountered in tunnel ionization using strong-field IR pulses. Including spin-orbit interaction does not change the qualitative feature and leads only to a reduction in the alignment by $2/3$. Our study is based on a time-dependent configuration-interaction singles (TDCIS) approach which solves the multichannel time-dependent Schr\"odinger equation.