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Title: Communication: He-tagged vibrational spectra of the SarGlyH{sup +} and H{sup +}(H{sub 2}O){sub 2,3} ions: Quantifying tag effects in cryogenic ion vibrational predissociation (CIVP) spectroscopy

To assess the degree to which more perturbative, but widely used “tag” species (Ar, H{sub 2}, Ne) affect the intrinsic band patterns of the isolated ions, we describe the extension of mass-selective, cryogenic ion vibrational spectroscopy to the very weakly interacting helium complexes of three archetypal ions: the dipeptide SarGlyH{sup +} and the small protonated water clusters: H{sup +}(H{sub 2}O){sub 2,3}, including the H{sub 5}O{sub 2}{sup +} “Zundel” ion. He adducts were generated in a 4.5 K octopole ion trap interfaced to a double-focusing, tandem time-of-flight photofragmentation mass spectrometer to record mass-selected vibrational predissociation spectra. The H{sub 2} tag-induced shift (relative to that by He) on the tag-bound NH stretch of the SarGlyH{sup +} spectrum is quite small (12 cm{sup −1}), while the effect on the floppy H{sub 5}O{sub 2}{sup +} ion is more dramatic (125 cm{sup −1}) in going from Ar (or H{sub 2}) to Ne. The shifts from Ne to He, on the other hand, while quantitatively significant (maximum of 10 cm{sup −1}), display the same basic H{sub 5}O{sub 2}{sup +} band structure, indicating that the He-tagged H{sub 5}O{sub 2}{sup +} spectrum accurately represents the delocalized nature of the vibrational zero-point level. Interestingly, the He-tagged spectrum of H{supmore » +}(H{sub 2}O){sub 3} reveals the location of the non-bonded OH group on the central H{sub 3}O{sup +} ion to fall between the collective non-bonded OH stretches on the flanking water molecules in a position typically associated with a neutral OH group.« less
Authors:
; ; ;  [1] ;  [2] ;  [1] ;  [3]
  1. Sterling Chemistry Laboratory, Yale University, 225 Prospect St., New Haven, Connecticut 06520 (United States)
  2. Department of Chemistry and Biochemistry, Fairfield University, 1073 North Benson Rd., Fairfield, Connecticut 06824 (United States)
  3. (United States)
Publication Date:
OSTI Identifier:
22420110
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 140; Journal Issue: 22; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; HELIUM COMPLEXES; HYDROGEN; MASS SPECTROMETERS; MOLECULES; OXONIUM IONS; PREDISSOCIATION; SPECTRA; SPECTROSCOPY; WATER