eprintid: 10103097
rev_number: 8
eprint_status: archive
userid: 695
dir: disk0/10/10/30/97
datestamp: 2020-06-29 12:29:56
lastmod: 2020-06-29 12:29:56
status_changed: 2020-06-29 12:29:56
type: thesis
metadata_visibility: show
creators_name: Stibbe, Darian Thorne
title: R-matrix calculations of vibrationally resolved electron collisions with molecular hydrogen
ispublished: unpub
keywords: Pure sciences
note: Thesis digitised by ProQuest.
abstract: Electron-H2 is the most basic, fundamental system for the study of electron collisions with molecules and has many interesting features. In particular, at low energy there is a shape resonance associated with the ground state and at higher energy a resonance associated with a dissociative target state. In the region of 10-15 eV there is an enormously complicated resonance structure due to the forest of electronically excited target states present, many of which have associated resonances. Despite a large number of experimental and theoretical studies, many ambiguities remain over the designation, symmetry assignment, parentage and behaviour of different isotopes of these '10 eV' resonances. The purpose of this work is to develop a full description of electron hydrogen molecule collisions at energies up to 14 eV with particular emphasis placed on the troublesome '10 eV' resonances. Ah initio fixed-nuclei scattering calculations have been performed for electron-H2 collisions as a function of H2 bond length using the R-matrix method, up to 2Φg total symmetry. The calculations include the seven lowest target states of H2 which are represented by full CI wavefunctions. The time-delay method of fitting has been developed during the course of this work. The use of this method has allowed the tracking of resonance positions and widths, and hence the production of resonance potential curves, where previous methods (most notably the fitting of the eigenphase sum) have failed due to problematic background variation. Several resonances in the 10-14 eV region have been found to be associated with multiple 'parent' target states and in some cases can swap parents as a function of bond length. These phenomena provide an explanation for the inconsistencies in previous assignments of resonances in this region and other anomalies. Vibrational energy levels have been found from the resonance potential curves and compared with experimental studies for H2, D2 and HD. The excellent agreement has allowed the production of a complete theoretical description of all the low-lying resonances. The agreement also provides corroboration of the multiple parent state/parent state swapping phenomena.
date: 1997
oa_status: green
full_text_type: other
thesis_class: doctoral_open
thesis_award: Ph.D
language: eng
thesis_view: UCL_Thesis
primo: open
primo_central: open_green
verified: verified_manual
full_text_status: public
pages: 131
institution: UCL (University College London)
thesis_type: Doctoral
citation:        Stibbe, Darian Thorne;      (1997)    R-matrix calculations of vibrationally resolved electron collisions with molecular hydrogen.                   Doctoral thesis  (Ph.D), UCL (University College London).     Green open access   
 
document_url: https://discovery.ucl.ac.uk/id/eprint/10103097/1/R-matrix_calculations_of_vibra.pdf