Attosecond transient-absorption spectroscopy of polar molecules

TL;DR

This paper uses attosecond transient absorption spectroscopy to investigate electron dynamics in polar molecules, revealing new spectral features caused by permanent dipoles, supported by theoretical models and simulations.

Contribution

It introduces the first observation of ladder structures in ATAS spectra of polar molecules and analyzes their origin using adiabatic state models.

Findings

Observation of light-induced structures near bright states in polar molecules

Identification of a new ladder structure in ATAS spectra

Theoretical analysis explains the origin of new spectral features

Abstract

We apply attosecond transient absorption spectroscopy (ATAS) to explore the effects of a nonzero permanent dipole on electron dynamics at the subfemtosecond scale, exemplified in the polar LiF molecule. In contrast with nonpolar systems, a familiar feature of the ATA spectra--the light-induced structures--are observed adjacent to a bright state. Moreover, a previously unobserved ladder structure is identified. The new observations are analyzed in the context of a model based on fixed-nuclei adiabatic states, supported by full numerical simulations. Analytic calculations originating in the adiabatic model shed light on the nature and origins of the new findings.