A. Trofimov, J. Schirmer, D. Holland
Dec 3, 2002
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0
Influential Citations
25
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Journal
Journal of Physics B
Abstract
The valence shell photoelectron spectrum of 2-iodothiophene (2-I-Th) has been studied experimentally and calculations have been carried out to characterize the main bands due to single-hole ionized states for both 2- and 3-iodothiophene. The importance of electron correlation in the formation of satellite states has also been assessed. The vertical ionization energies and spectral intensities of the entire valence shell photoelectron spectrum have been computed using the third-order algebraic–diagrammatic construction approximation for the one-particle Green function. These theoretical predictions have allowed assignments to be proposed for all the prominent structure observed in the experimental spectra, and have highlighted the breakdown of the molecular orbital model of ionization for the π1-orbital. By comparing the present theoretical and experimental results for iodothiophene with similar data for chloro-and bromothiophene, it has been found that the binding energies and intensities of the satellites associated with the π1-orbital form a pattern which is common to all three monohalothiophenes. Relativistic Hartree–Fock calculations have been carried out to investigate the importance of such effects on the valence shell ionization of iodothiophene. Synchrotron radiation has been used to measure photoelectron angular distributions and branching ratios of 2-I-Th. The spectral behaviour of the asymmetry parameters has provided an experimental means of distinguishing photoelectron bands due to σ-orbitals from those associated with π-orbitals. A high-resolution photoelectron spectrum of the outer valence shell of 2-I-Th has been recorded using HeI radiation, and vibrational structure has been observed and analysed in the 2A'', A 2A'', 2A' and 2A'' state bands.