Theory of nuclear motion in RABBITT spectra

TL;DR

This paper develops a general, computationally feasible theory for interpreting RABBITT spectra in molecules, linking spectral features to vibronic dynamics and two-electron photoionization processes.

Contribution

The authors derive a convolution-based theoretical framework for molecular RABBITT spectra, enabling more accurate modeling and interpretation.

Findings

RABBITT spectra can be expressed as a convolution of vibronic cross-correlation functions and two-electron photoionization matrix elements.

Special cases of the general theory are identified and analyzed.

The theory facilitates improved understanding of molecular internal dynamics from RABBITT measurements.

Abstract

Reconstruction of attosecond beating by interference of two-photon transitions (RABBITT) is a powerful photoelectron spectroscopy, offering direct access to internal dynamics of the target. It is being increasingly applied to molecular systems, but a general, computationally tractable theory of RABBITT spectra in molecules has so far been lacking. We show that under quite general assumptions, RABBITT spectra in molecules can be expressed as a convolution of the vibronic cross-correlation functions and two-electron photoionization matrix elements. We specialize the general expressions to the commonly-encountered special cases. We expect our theory to enable accurate modeling and interpretation of molecular RABBITT spectra in most medium-sized molecules.