Opportunities for detecting ring currents using the attoclock set-up

TL;DR

This paper demonstrates that few-cycle IR pulses combined with the attoclock setup can detect ring currents in atoms and molecules by observing angular shifts in ejected electrons, revealing differences between counter-rotating orbitals.

Contribution

It introduces a method to detect ring currents via attoclock angular shifts using time-dependent Analytical R-Matrix theory, highlighting differences between counter-rotating orbitals.

Findings

Angular shifts differ for electrons from $p^{+}$ and $p^{-}$ orbitals.

Application of few-cycle IR pulses enhances detection of ring currents.

The method opens new avenues for studying quantum states in atoms and molecules.

Abstract

Strong field ionization by circularly polarized laser fields from initial states with internal orbital momentum has interesting propensity rule: electrons counter-rotating with respect to the laser field can be liberated more easily than co-rotating electrons [Barth and Smirnova PRA 84, 063415, 2011}]. Here we show that application of few-cycle IR pulses allows one to use this propensity rule to detect ring currents associated with such quantum states, by observing angular shifts of the ejected electrons. Such shifts present the main observable of the attoclock method. We use time-dependent Analytical $R$-Matrix (A$R$M) theory to show that the attoclock measured angular shifts of an electron originating from two counter-rotating orbitals ($p^{+}$ and $p^{-}$) are noticeably different. Our work opens new opportunities for detecting ring currents excited in atoms and molecules, using the attoclock set-up.