Infrared spectra of protonated pyrene and its neutral counterpart in solid para-hydrogen

Mohammed Bahou, Yu Jong Wu*, Yuan-Pern Lee

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Protonated polycyclic aromatic hydrocarbons (H+PAHs) have been reported to have infrared (IR) bands at wavenumbers near those of unidentified infrared (UIR) emission bands from interstellar objects. We produced 1-C 16H11+ and 1-C16H11 upon electron bombardment during matrix deposition of p-H2 containing pyrene (C16H10) in a small proportion. Intensities of absorption features of 1-C16H11+ decreased after the matrix was maintained in darkness or irradiated with light at 365 nm, whereas those of 1-C16H11 increased. The observed line wavenumbers and relative intensities of 1-C16H11 + and 1-C16H11 agree satisfactorily with the scaled vibrational wavenumbers and IR intensities predicted with the B3PW91/6-311++G(2d,2p) method. Our method, being relatively clean with negligible fragmentation, is applicable to larger H+PAH; it has the advantages of producing excellent IR spectra covering a broad spectral range with narrow lines and accurate intensities, so that structural identification among various isomers is feasible.

Original languageEnglish
Pages (from-to)1989-1993
Number of pages5
JournalJournal of Physical Chemistry Letters
Issue number12
StatePublished - 20 Jun 2013


  • C H
  • CH
  • IR spectroscopy
  • matrix isolation
  • p -H
  • pyrene

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