Modifications in the angular photoemission time delay in Ar@C60q=−1 : Coulomb confinement resonance as an amplifier of the spin-orbit-interaction-activated interchannel coupling effect

Abstract

Coulomb confinement resonances (CCRs) are the main features of the photoionization spectra of an atom inside an anionic fullerene. These CCRs can act as an amplifier to spin-orbit-interaction-activated interchannel coupling (SOIAIC) and can lead to discernible signatures of relativistic effects even for low $Z$ confined atomic systems. The present paper demonstrates this intriguing feature by studying angular photoemission time delay of the $2{p}_{3/2}$ subshell of $\mathrm{Ar}@{\mathrm{C}}_{60}^{\ensuremath{-}1}$ in the vicinity of the $2{p}_{1/2}$ ionization threshold. Here $2{p}_{1/2}$ CCR functions as an amplifier to the SOIAIC and, thereby, induces significant modifications in the $2{p}_{3/2}$ angular time delay through the interchannel coupling. Moreover, the effects of the SOIAIC for the spin-up and spin-down photoelectrons are found to be different. All of these suggest that angle-resolved time-delay measurements can reveal the relativistic effects even for the low Z confined atomic systems, and $\mathrm{Ar}@{\mathrm{C}}_{60}^{\ensuremath{-}1}$ is a potential candidate for such experimental scrutiny. The impact of the model parameters on the predicted feature is also critically examined by using different sets of parameters. All of those calculations showed the existence of SOIAIC enabled structures in the angular time-delay profile.