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Title: Experimental and computational investigation of molecular photodissociation and scattering dynamics
Author: Cascarini, Fred J. J.
ISNI:       0000 0005 0294 175X
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2021
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This thesis reports new research performed during the development and characterisation of an improved scattering chamber in an existing velocity map imaging (VMI) apparatus. These studies consist of an investigation into the photodissociation of 2,4-dibromofluorobenzene (DBFB), inelastic scattering of NO with methane, and progress towards reactive scattering. Quasi-classical trajectory (QCT) studies have also been performed on the reaction of chlorine atoms with propene. The QCT studies of the reaction of chlorine atoms with propene investigated the effect of collision energy variation. The characteristics of the reaction were determined at collision energies of 7, 14 and 28 kJ mol⁻¹, in terms of the product HCl rotational and vibrational population distributions, opacity functions, differential cross sections, and the trajectory durations. The pathways taken by the trajectories across the reactive potential energy surface were analysed at each collision energy, identifying the relative importance of different mechanisms. Studies of DBFB characterised the production of bromine atoms through photodissociation in the region 260 - 285 nm. This work utilised Resonance Enhanced Multi-Photon Ionisation (REMPI) of the bromine product, followed by either photofragment excitation spectroscopy or VMI. Assignment of the dissociative pathways was assisted by quantum chemical computations and by comparison with simpler bromofluorobenzenes. The inelastic scattering of NO with methane was studied at a mean collision energy of 700 cm⁻¹. State-selective differential cross sections of scattered NO were determined using REMPI followed by VMI detection. The mechanistic implications of these cross sections are discussed, with reference to rotational rainbow theory and the observation of anticorrelated rotational energy levels for the scattered collision partners. Finally, progress towards reactive scattering using the improved apparatus is reported. This includes the reliable production of cyanogen radicals, in preparation for an anticipated study on the reactive scattering of cyanogen radicals with methane.
Supervisor: Orr-Ewing, Andrew Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available