Infrared spectroscopy of H+(CO)(2) in the gas phase and in para-hydrogen matrices

Daniel Leicht, Brandon M. Rittgers, Gary E. Douberly, J. Philipp Wagner, David C. McDonald, Daniel T. Mauney, Masashi Tsuge, Yuan-Pern Lee, Michael A. Duncan*

*Corresponding author for this work

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Abstract

The H+(CO)(2) and D+(CO)(2) molecular ions were investigated by infrared spectroscopy in the gas phase and in para-hydrogen matrices. In the gas phase, ions were generated in a supersonic molecular beam by a pulsed electrical discharge. After extraction into a time-of-flight mass spectrometer, the ions were mass selected and probed by infrared laser photodissociation spectroscopy in the 700 cm(-1)-3500 cm(-1) region. Spectra were measured using either argon or neon tagging, as well as tagging with an excess CO molecule. In solid para-hydrogen, ions were generated by electron bombardment of a mixture of CO and hydrogen, and absorption spectra were recorded in the 400 cm(-1)-4000 cm(-1) region with a Fourier-transform infrared spectrometer. A comparison of the measured spectra with the predictions of anharmonic theory at the CCSD(T)/ANO1 level suggests that the predominant isomers formed by either argon tagging or para-hydrogen isolation are higher lying (+7.8 kcal mol(-1)), less symmetric isomers, and not the global minimum proton-bound dimer. Changing the formation environment or tagging strategy produces other non-centrosymmetric structures, but there is no spectroscopic evidence for the centrosymmetric proton-bound dimer. The formation of higher energy isomers may be caused by a kinetic effect, such as the binding of X (=Ar, Ne, or H-2) to H+(CO) prior to the formation of X H+(CO)(2). Regardless, there is a strong tendency to produce non-centrosymmetric structures in which HCO+ remains an intact core ion.

Original languageEnglish
Article number084305
Number of pages16
JournalJournal of Chemical Physics
Volume153
Issue number8
DOIs
StatePublished - 28 Aug 2020

Keywords

  • PROTON-BOUND DIMERS
  • PHOTODISSOCIATION SPECTROSCOPY
  • LASER SPECTROSCOPY
  • CLUSTER IONS
  • PREDISSOCIATION SPECTROSCOPY
  • VIBRATIONAL SPECTROSCOPY
  • MASS-SPECTROMETER
  • FUNDAMENTAL-BAND
  • BONDED CLUSTERS
  • MOLECULAR-IONS

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