Measuring molecular dynamics using UV and XUV photoelectron spectroscopy

Abstract

Time resolved photoelectron spectroscopy (TRPES) is a valuable method for measuring molecular dynamics on the necessary femtosecond timescales. This thesis describes TRPES measurements of methyl iodide and carbon disulphide, along with the equipment and capabilities required for these measurements.

The photodissociation dynamics of methyl iodide are observed using both UV and XUV probes. UV excitation at 269 nm leads to population of the 3Q0 state, and we observe a simple, rapid dissociation in this state, which is in agreement with previous measurements. With both the UV and the XUV probes, we see a short lifetime for this dissociation, of around 30 fs. The XUV probe allows the dynamics to be followed for a longer time, and a shifting feature in the time resolved spectrum maps the motion of the excited wavepacket on the 3Q0 potential energy surface.

The dynamics of CS2 following photoexcitation are measured using an XUV probe, and this allows for a complete measurement of the dissociation dynamics of the molecule, including the competing internal conversion and intersystem crossing pathways. Ground state depletion, transient excited state signals, and the formation of the dissociation products are all seen in the time resolved photoelectron spectra.

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Identifiers

ORCID for Russell Minns: orcid.org/0000-0001-6775-2977

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