The electronic states of pyrrole studied by optical (VUV) absorption, near-threshold electron energy-loss (EEL) spectroscopy and ab initio multi-reference configuration interaction calculations

Michael H. Palmer, Isobel C. Walker, Martyn F. Guest

Research output: Contribution to journalArticle

99 Citations (Scopus)

Abstract

A reinvestigation and extension of the observed VUV and EEL spectrum of pyrrole has been carried out, and the spectra assigned by means of high level multi-reference multi-root CI studies. A similar reasssessment of the UV-photoelectron spectrum leads to the conclusion that our previous assignment of IP3 to ionisation of the inner p-level (1b1) is correct and that most other assignments to ionisation of a s-electron are incorrect. This is supported by the calculation of a wide range of Rydberg states derived from the five least bound orbitals, in the IP order: 1a2-1 < 2b1-1 < 1b1-1 < 9a1-1 < 6b2-1 < 5b2-1 < 8a1-1 < 7a1-1 < 4b2-1. It is concluded that each of the two strong absorption bands centred around 6 and 7.5 eV respectively owe their intensity to excitation of two 1pp* states of symmetry 1A1 and 1B2. The range of calculated valence states of pp*-type has been extended to include those from 1b1.

Original languageEnglish
Pages (from-to)179-199
Number of pages21
JournalChemical Physics
Volume238
Issue number2
Publication statusPublished - 15 Nov 1998

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