A fast and streamlined method for the measurement of absolute photodetachment and photodissociation cross-sections

TL;DR

This paper introduces a rapid, efficient method for measuring absolute photodetachment cross-sections of molecular ions, significantly reducing measurement time and enabling studies on biologically relevant molecules, with implications for databases and computational modeling.

Contribution

A novel streamlined technique combining experimental rate measurement with simulations to measure photodetachment cross-sections, including for complex biological molecules.

Findings

Validated method reproduces known cross-section for OH^-

First measurement of deprotonated indole at 403 nm

Potential to accelerate database development and computational modeling

Abstract

The absolute photodetachment cross-section characterizes the photostability of atomic and molecular anions against photodestruction by neutralization. The measurement of this quantity has been reported only for atomic and simple molecular ions. In 2006, Wester's group introduced a novel ion-trap-based technique to measure the absolute photodetachment cross-section [S. Trippel et al., Phys. Rev. Lett. 97, 193003 (2006)] of OH^-. In the present work, we propose a novel methodology to streamline this technique to reduce the measurement time by several orders of magnitude by combining a single experimental rate measurement with a simulated column density distribution of the trapped ions. We validated our approach by reproducing the cross-section reported for OH^- at 632.8 nm. Using this technique, we report the first such measurement for a molecule of biological interest, deprotonated indole, at a laser wavelength of 403 nm. The proposed scheme is anticipated to have a significant and transformative impact on the development of a comprehensive database for photodetachment and photodissociation cross-sections of molecular ions. Furthermore, these measurements have the potential to drive the development of cutting-edge computational codes for cross-section calculations, enabling an unprecedentedly detailed understanding of electron dynamics in large molecules and the light-matter interaction.