Nonadiabatic effects in attosecond transient absorption spectroscopy

TL;DR

This paper investigates how nonadiabatic couplings influence attosecond transient absorption spectra in a diatomic molecule model, identifying regimes where these effects are significant or negligible.

Contribution

It introduces a model with four diabatic states to analyze nonadiabatic effects across different vibronic coupling regimes in attosecond spectroscopy.

Findings

Nonadiabatic couplings can significantly alter spectra in certain regimes.

A multilevel model effectively explains the interplay of electronic and nuclear dynamics.

The study delineates when nonadiabatic effects can be safely ignored.

Abstract

We study effects of nonadiabatic couplings in a model of a diatomic molecule in the context of attosecond transient absorption spectroscopy. By using a model system consisting of four diabatic electronic states and with a variable strength of the diabatic coupling, we can explore attosecond transient absorption spectra in different regimes of the vibronic couplings between the electronic and nuclear dynamics, and determine when nonadiabatic couplings can be ignored or when they have a substantial effect. The findings are rationalized in terms of a multilevel model, which captures aspects of both electronic and nuclear degrees of freedom.