Some studies in electron spectroscopy

Fayad, Noori K (1980) Some studies in electron spectroscopy. University of Southampton, Doctoral Thesis.

Abstract

The theoretical methods which have been used throughout the course of this project are described briefly In Chapter 1. The MS Xa transition state was also used to determine the ionization potentials and the charge distribution of the actinide tetrafluorides. The spectrometer used in this work, for the study by p.e.s of small molecules generated by fluorine abstraction and high temperature pyrolysis is described. The r.f. induction furnace used to pyrolyze solid samples inside the ionization chamber of the above spectrometer is also described. The IF and BrF molecules were produced by the fluorine-atom abstraction method and studied by p.e s Each molecule exhibits three bands in the Hal region. The first band observed for each molecule is split into two components by spin-orbit coupling corresponding to ionization to the X'llL and X'ii ionic states. Estimates of re we and De for these states have been made. The Hel photoelectron spectrum of the hydrogen sulphide radical produced by the reaction F +H, S-+ SH + HF has also been studied. It shows ionizations corresponding to the production of SH+ in the states X'E','a,'Et 3f and 'B at ionization potentials of 10.42, 11.67, 12.24, 14.13 and 15.58 eV respectively. Also, the photoelectron spectrum of sulphur atoms has been recorded. The S atoms were produced from the reaction SH + F -. S + HF. The gas-phase helium photoelectron spectra of the actinide tetrafluoudes UF4, ThE4, UCH and ThC14 have been recorded. The spectra have been interpreted with the aid of nonrelativistic multiple-scattering SCF-X, calculations and are consistent with an effective tetrahedral geometry for these molecules in the gas phase. Both the calculations and the spectra indicate that the 5f electrons in UF4 and UCIM are essentially localised on the central metal. The Hel photoelectron spectra of the transition metals Cu, Ag, Au, Cr and Mn were recorded in the gas-phase. The solid samples were vapourized in the temperature range of (1300 - 2450)IG In the manganese spectrum, satellite structure was also seen in addition to the formally allowed one-electron ionization Measurement of the relative intensities of the allowed bands has led to values of the ions : o(n-1)d photoionization cross-section ratios recorded at right angles to the photon beam. Some preliminary investigations of the transition metal oxides (TiO (X 'n) and CrO (X'10 ) have also been performed. Also, the Hel (21.21 eV) and Hell (40.8 eV) photoelectron spectra of CuF, and ZnF3 were recorded in general, no enhancement. the photoionization cross section of the transition metal 3d orbitals has been observed, compared with orbitals of predominantly F 2p character on going from Hel to Hell radiation. In Chapter 9, the design of a Penning ionization source is presented, which includes a water-cooled electron impact source to produce helium metastables. Some improved Penning electron spectra were recorded for argon.

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