Photoelectron imaging of the SO₃ anion: vibrational resolution in photoelectron angular distributions*

Abstract

The photoelectron imaging of the pyramidal sulphite radical monoanion is presented in the photon energy range spanning 3.10–4.45 eV. Two features are seen corresponding to formation of the ground electronic state of the neutral and to thermionic emission, which is seen for hv > 3.7 eV. Photoelectron spectra corresponding to direct detachment show vibrational structure associated with the v₂ umbrella mode of the neutral. A similar structure is seen in the photoelectron angular distributions. The photoelectron angular distributions were modelled and agree with experiment. However, we cannot provide an explanation for the observed vibrational structure in the photoelectron angular distributions. The observed thermionic emission is assigned to the excitation to a pair of degenerate Feshbach resonances, which can internally convert and subsequently emit electrons statistically.

GRAPHICAL ABSTRACT

KEYWORDS:

• Photoelectron angular distributions
• velocity map imaging
• photoelectron spectroscopy

Acknowledgement

We thank Chris Sparling and Dave Townsend (Heriot-Watt University) for analysing photoelectron images using different methodologies and for insightful discussions. We are grateful to the European Research Council (306536) for funding.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by FP7 Ideas: European Research Council: [Grant Number 306536].