Ionic and Rydberg states of CF3I studied by high resolution photoelectron (ZEKE-PFI) and resonance-enhanced multiphoton ionisation spectroscopy

NA Macleod, S Wang, J Hennessy, T Ridley, KP Lawley*, RJ Donovan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Ionic and Rydberg states of CF3I have been studied using both zero kinetic energy pulsed-field ionisation (ZEKE-PFI) photoelectron and resonance-enhanced multiphoton ionisation (REMPI) spectroscopy. The ground state of the ion ((X) over tilde E-2(3/2)) was characterised using coherent two-photon (one-colour) ZEKE-PFI spectroscopy and extended progressions in the symmetric vibrational modes, similar to those observed in the conventional He(I) photoelectron spectrum, were observed at high resolution. The [E-2(3/2)]6p Rydberg states were studied using two- and three-photon REMPI spectroscopy with linearly and circularly polarised light. This resulted in the assignment of at least three states with distinct Omega values (2, 1 and 0) with the Omega = 2 components being the most intense. The strongest members of the [E-2(3/2)]6p;2 system were used as resonant intermediates in two-colour (2 + 1') ZEKE-PFI experiments which allowed the unambiguous assignment of the majority of the vibrational structure of the intermediate states. The adiabatic ionisation energy of CF,I was determined as 83652 +/- 2 cm(-1) The vibrational structure observed for one of the SZ = 2 components of the [E-2(3/2)]6p cluster in CF3I differs considerably from that observed for the lower lying 6s states and the analogous 6p states of CH3I. In particular, nu(3) (the carbon-iodine stretch) shows a vibrational frequency substantially reduced from that of the neutral and ionic ground states. It is concluded that at least one of the [E-2(3/2)]6p states of CF3I is distorted, possibly through an interaction with an ion-pair state.

Original languageEnglish
Pages (from-to)2689-2694
Number of pages6
JournalJournal of the Chemical Society, Faraday Transactions
Volume94
Issue number18
Publication statusPublished - 21 Sep 1998

Keywords

  • ENERGY PHOTOELECTRON
  • IONIZATION SPECTRUM
  • METHYL-IODIDE
  • CH3I
  • POLARIZATION
  • MOLECULES
  • REGION
  • CD3I

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