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Title: Light emissions accompanying molecular double photoionisation
Author: Taylor, S. N.
ISNI:       0000 0004 2725 6954
Awarding Body: Oxford University
Current Institution: University of Oxford
Date of Award: 2006
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A new triple coincidence experiment has been developed for the sensitive detection of ionic emissions and is an extension of the Photo Ion - Fluorescence Coincidence experiment (PIFCO), with the additional coincident detection of the photoelectron (PEPIFCO). This has enabled the discovery of two new fluorescent dications (CS22+ and N2 O2+) and has also revealed many new fragment emissions. To - analyse and interpret these dication emissions, stable/metastable excited states were identified by another new experiment involving the coincident detection of energy analysed electron-pairs with one or two photoions. These states were assigned with the aid of potential energy curves constructed from large MRCI computations, which were also used to predict and rationalise the dynamical behaviour of each electronic state. The fluorescent electronic states were also observed directly in a third new coincidence experiment involving the detection of energy analysed electron-pairs with fluorescence photons (PEPEFCO). For CS22+, the two separate transitions identified were 13Σu- ~ X3 Σ g and 11Λu ~ llΔL1g and for N202+, observed emission is attributed to the 13 Π ~ X3L- transition and perhaps also the 23 Π ~ X3L- transition. When the target molecules were ionised by photons exceeding 40 eV, many new fragment emissions were observed, including several coincident with charge separated fragments from dications. These fragment emissions have been analysed using the PEPIFCO experiment in combination with optical filters and the PEPEFCO apparatus, which is also a sensitive multiplex PEFCO spectrometer. Interpretations have been given for each emission, including assignments of specific electronic transitions and often their appearance energies also. Finally, the existence of an emission from the acetylene cation which we attribute to the 12Π, ~ x'n, transition is confirmed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available