Imaging the Renner-Teller effect using laser-induced electron diffraction

TL;DR

This paper demonstrates the use of laser-induced electron diffraction to directly image the ultrafast structural dynamics of excited neutral CS$_2$ molecules, revealing bending and stretching with high temporal and spatial resolution.

Contribution

It provides the first direct structural retrieval of the B$^1$B$_2$ excited state of neutral CS$_2$ using LIED, highlighting its sensitivity to molecular geometry changes.

Findings

Ultrafast symmetric stretching and bending of CS$_2$ observed.

High-resolution measurement with picometer and attosecond precision.

Confirmation of the Renner-Teller effect's role in excited state geometry.

Abstract

Structural information on electronically excited neutral molecules can be indirectly retrieved, largely through pump-probe and rotational spectroscopy measurements with the aid of calculations. Here, we demonstrate the direct structural retrieval of neutral carbonyl disulfide (CS$_2$) in the B$^1$B$_2$ excited electronic state using laser-induced electron diffraction (LIED). We unambiguously identify the ultrafast symmetric stretching and bending of the field-dressed neutral CS$_2$ molecule with combined picometer and attosecond resolution using intrapulse pump-probe excitation and measurement. We invoke the Renner-Teller effect to populate the B$^1$B$_2$ excited state in neutral CS$_2$, leading to bending and stretching of the molecule. Our results demonstrate the sensitivity of LIED in retrieving the geometric structure of CS$_2$, which is known to appear as a two-center scatterer.