Bonn 2025 – scientific programme

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SYML: Symposium Molecular Spectroscopy of Liquid Jets

SYML 1: Molecular Spectroscopy in Liquid Jets

SYML 1.3: Invited Talk

Monday, March 10, 2025, 12:00–12:30, HS 1+2

UV photoelectron spectroscopy of aqueous solutions — •Helen Fielding, Johanna Rademacher, Kate Robertson, and Edoardo Simonetti — Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.

Ionisation and electron transfer processes are ubiquitous in condensed-phase biology and atmospheric chemistry. It is, therefore, essential to measure the electronic structure and UV photoexcited state dynamics of biologically and atmospherically important chromophores in conditions similar to those encountered in nature, i.e. in aqueous solution. A direct way of probing electronic structure, and its evolution following photoexcitation, is through the measurement of electron binding energies using photoelectron spectroscopy. However, there are a number of practical challenges associated with carrying out such measurements in aqueous solution using UV light pulses. These include electrokinetic charging, vacuum level offsets, uncertainties in instrument functions at very low electron kinetic energies (< 1 eV), and the need to account for distortions of measured electron kinetic energy distributions arising from inelastic scattering of low energy electrons (< 5 eV) in liquid water. We will present our approach to accurate UV photoelectron spectroscopy measurements in aqueous solution and its application to biologically and atmospherically relevant chromophores.

Keywords: photoelectron spectroscopy; chromophores; aqueous solutions