The vibrational predissociation spectroscopy of hydrogen cluster ions

• Published in: The Journal of chemical physics 1985-01, Vol.83 (7), p.3705-3706
• Main Authors: OKUMURA, M, YEH, L. I, LEE, Y. T
• Format: Article
• Language: English
• Subjects: 640302 - Atomic, Molecular & Chemical Physics- Atomic & Molecular Properties & Theory; AGGLOMERATION; Atomic and molecular clusters; ATOMIC AND MOLECULAR PHYSICS; CHARGED PARTICLES; DISSOCIATION; ENERGY LEVELS; Exact sciences and technology; EXCITED STATES; HYDROGEN IONS; INFRARED SPECTRA; IONS; MOLECULAR IONS; Physics; PREDISSOCIATION; SPECTRA; Studies of special atoms, molecules and their ions; clusters; VIBRATIONAL STATES
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.449127

The first infrared spectra of protonated hydrogen clusters in the gas phase have been observed. Predissociation spectra were taken with a tandem mass spectrometer: mass selected hydrogen cluster ions were irradiated inside a rf ion trap by a tunable infrared laser, and the fragment ions created by photodissociation of the clusters were mass selected and detected. Spectra for each product channel were measured by counting fragment ions as a function of laser frequency. Low resolution spectra (Δν=10 cm−1) in the region from 3800 to 4200 cm−1 were observed for the ions H+5, H+7, and H+9 at 3910, 3980, and 4020 cm−1, respectively. A band was also observed for H+5 at 3532 cm−1. No rotational structure was resolved. The frequencies of the band maxima agree well with the frequencies predicted by previous ab initio calculations for the highest modes.