Interpretation of the photoelectron, ultraviolet, and vacuum ultraviolet photoabsorption spectra of bromobenzene by ab initio configuration interaction and DFT computations

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DOI

  • Michael H. Palmer, Univ Edinburgh, University of Edinburgh, Sch Chem
  • ,
  • Trevor Ridley, Univ Edinburgh, University of Edinburgh, Sch Chem
  • ,
  • Soren Vrønning Hoffmann
  • Nykola C. Jones
  • Marcello Coreno, CNR IMIP
  • ,
  • Monica de Simone, CNR IOM Lab TASC
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  • Cesare Grazioli, Univ Trieste, University of Trieste, Dept Chem & Pharmaceut Sci
  • ,
  • Teng Zhang, Uppsala Univ, Uppsala University, Dept Phys & Astron
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  • Malgorzata Biczysko, Scuola Normale Super Pisa, Scuola Normale Superiore di Pisa
  • ,
  • Alberto Baiardi, Scuola Normale Super Pisa, Scuola Normale Superiore di Pisa
  • ,
  • Kirk Peterson, Washington State Univ, Washington State University, Dept Chem

New photoelectron, ultraviolet (UV), and vacuum UV (VUV) spectra have been obtained for bromobenzene by synchrotron study with higher sensitivity and resolution than previous work. This, together with use of ab initio calculations with both configuration interaction and time dependent density functional theoretical methods, has led to major advances in interpretation. The VUV spectrum has led to identification of a considerable number of Rydberg states for the first time. The Franck-Condon (FC) analyses including both hot and cold bands lead to identification of the vibrational structure of both ionic and electronically excited states including two Rydberg states. The UV onset has been interpreted in some detail, and an interpretation based on the super-position of FC and Herzberg-Teller contributions has been performed. In a similar way, the 6 eV absorption band which is poorly resolved is analysed in terms of the presence of two pi pi* states of (1)A(1) (higher oscillator strength) and B-1(2) (lower oscillator strength) symmetries, respectively. The detailed analysis of the vibrational structure of the 2(2)B(1) ionic state is particularly challenging, and the best interpretation is based on equation-of-motion-coupled cluster with singles and doubles computations. A number of equilibrium structures of the ionic and singlet excited states show that the molecular structure is less subject to variation than corresponding studies for iodobenzene. The equilibrium structures of the 3b(1)3s and 6b(2)3s (valence shell numbering) Rydberg states have been obtained and compared with the corresponding ionic limit structures. (C) 2015 AIP Publishing LLC.

Original languageEnglish
Article number164303
JournalJournal of Chemical Physics
Volume143
Issue16
Number of pages18
ISSN0021-9606
DOIs
Publication statusPublished - 2015

    Research areas

  • GAUSSIAN-BASIS SETS, CORRELATED MOLECULAR CALCULATIONS, FLUOROBENZENE RADICAL-CATION, DENSITY-FUNCTIONAL THEORY, ELECTRONIC STATES, PHOTODISSOCIATION MECHANISM, VIBRONIC INTERACTIONS, EXCITATION-ENERGIES, ABSORPTION-SPECTRA, RYDBERG STATES

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