Trevisan, Cynthia Sandra;
(2002)
Near-threshold electron impact dissociation of molecular hydrogen.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Electron impact dissociation of molecular hydrogen is considered to be a major route to molecular break-up in cool hydrogen plasmas. Such plasmas are found in a number of astrophysical environments and in the divertor region of tokamak fusion plasma. At low energies, the major pathway for the electron impact dissociation of H₂ is through excitation to the b ³Σ⁺u dissociative excited electronic state. The purpose of this work is to develop a theoretical formulation for this process for an arbitrary diatomic molecule, and to derive the formal expressions that describe the differential and total cross sections, which involve three fragments in the exit channel, and to study the electron impact dissociation of molecular hydrogen and its isotopomers at near-threshold energies. Ab initio calculations of total cross sections, angular differential cross sections, energy differential cross sections and double differential cross sections are made for the v = 0 vibrational level of H₂. The effect of nuclear motion is then included in such calculations, with the dissociation taking place from the electronic ground state at different initial vibrational levels, dissociating into continuum states. Studies of mixed isotopes are performed using the R-matrix method, and total cross sections, energy differential cross sections and rate coefficients for electron impact dissociation of H₂, D₂, T₂, HD, HT and DT as a function of the vibrational states are presented. Finally, a scaling rule that describes integral cross sections as a function of the initial vibrational state, the reduced mass of the target molecule and the energy of the projectile electron is developed and compared against cross sections calculated accurately for the H₂ molecule and its isotopomers.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Near-threshold electron impact dissociation of molecular hydrogen |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Thesis digitised by ProQuest. |
| Keywords: | Pure sciences; Electron impact dissociation |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10103238 |
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