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dc.contributor.authorMacGregor, Donald Mansonen
dc.date.accessioned2019-02-15T14:33:59Z
dc.date.available2019-02-15T14:33:59Z
dc.date.issued1967en
dc.identifier.urihttp://hdl.handle.net/1842/35025
dc.description.abstracten
dc.description.abstractThe adsorption mechanisms proposed here have involved interaction of gas and sorbate phase molecules or ions with three different kinds of active sites - electron donors, 'shallow' traps and deeper-lying trapping centres associated with molecular water. The shallow traps have been tentatively identified with oxygen - vacancies, and the donors and deep traps with hydroxyl-vacancies. The band-structure of the solid-surface may be modified to include the deep traps, or sinks, which may lie just above or below the donor levels, depending on the exo- or endo-thermal nature of the reactionen
dc.description.abstractInterpretation of the photo-adsorption data has here been in terms of an overall scheme which is basically a compound of previously suggested ideas. For example, the 'A' and 'B'-site concept of Kennedy (2) has been largely retained, including the migration-controlled O₂ uptake mechanism, though the proposed nature of the donors and "oxygen sites" is more akin to the ideas of McLean (3). Similarities also exist to the other reaction schemes of McLintock (4) and Bews (17): but it is felt that the present scheme is more comprehensive than formerly, being capable, for example, of embracing many diverse features of the interrelated oxygen, hydrocarbon and nitric oxide uptakes. No claim is made, however, to have provided a unique explanation of the intricacies involved in the photosorptions. It is merely suggested that the treatment described in the previous pages serves as a reasonable account of the electronic processes that may occur within the surface layers under illumination. Proof that these processes do occur is not possible at the present level of experimental investigation, but some degree of confirmation may have been achieved from the quantitative approach towards predicted C₂H₄ uptake values, and free donor concentrations.en
dc.description.abstractFuture investigation might be directed at elucidating the nature of the finally sorbed species. For example, infra-red A.T,R. techniques might be developed in order to examine the hydrocarbon-surface bond, and the possible presence of CH₃ groups on ethylene-covered surfaces. Magnetic susceptibility measurements could well provide valuable information on the concentration of paramagnetic centres (e.g. O.) in the dark, under illumination, and in the presence of various adsorbates, and hence might settle the nature of surface oxygen. Extension of photoconductivity measurements of the type made by McLintock (4) to include a study of the NO sorption would also be of interest, and the origin of photodesorbed H₂O might profitably be examined, using labelling techniques.en
dc.publisherThe University of Edinburghen
dc.relation.ispartofAnnexe Thesis Digitisation Project 2019 Block 22en
dc.relation.isreferencedbyen
dc.titlePhotochemical reactions of titanium dioxideen
dc.typeThesis or Dissertationen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD Doctor of Philosophyen


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