Threshold ionization and dissociation of t-butylamine

Paul M. Mayer, Martyn F. Guest, Emma E. Rennie, Louise Cooper, Larisa G. Shpinkova, D. M P Holland, David A. Shaw

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The threshold photoelectron spectrum of t-butylamine, recorded between 8 and 28 eV, is reported for the first time. The spectrum was compared to orbital ionization energies calculated at the OVGF/cc-pVTZ level of theory. The adiabatic and vertical ionization energies of the outermost orbital (made up primarily of the nitrogen p orbital) are 8.48 ± 0.02 and 9.40 ± 0.02 eV, respectively. Threshold photoelectron photoion coincidence spectra were recorded between 8.5 and 35 eV, and appearance energies for 15 fragment ions were obtained. The lowest energy dissociation is the loss of a methyl group to form the (CH3)2CNH2 + ion. RRKM fitting of this dissociation leads to a ?fH298 for (CH3)2CNH2 + of 603 ± 3 kJ mol-1. This value is ~10 kJ mol-1 higher than the previously derived value of Lossing et al. (based on an electron ionization appearance energy value) and the G3B3 estimate. Together with the proton affinity value of 932.3 kJ mol-1, the present ?fH298 leads to a ?fH298 for 2-propanimine (CH3)2C=NH of 5.3 kJ mol-1, which can be compared to a value of -5.7 kJ mol-1 (based on the Lossing et al. (CH3)2CNH2 + ?fH298) and a G3B3 value of -0.3 kJ mol -1. At photon energies above 26 eV, there is evidence for the dissociative double ionization of t-butylamine forming either the singlet or triplet state of the dication.

Original languageEnglish
Pages (from-to)142-149
Number of pages8
JournalCanadian Journal of Chemistry
Volume88
Issue number2
DOIs
Publication statusPublished - Feb 2010

Keywords

  • Ab initio molecular orbital calculations
  • Activation energies
  • Activation entropies
  • Density functional calculations
  • Ionization energies
  • T-butylamine ions
  • Threshold photoelectron photoion coincidence spectroscopy

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