title: Infrared spectroscopy and tunneling dynamics of the vinyl radical in 4He nanodroplets.
abstract: The vinyl radical has been trapped in (4)He nanodroplets and probed with infrared laser spectroscopy in the CH stretch region between 2850 and 3200 cm(-1). The assigned band origins for the CH2 symmetric (ν3), CH2 antisymmetric (ν2), and lone α-CH stretch (ν1) vibrations are in good agreement with previously reported full-dimensional vibrational configuration interaction computations [A. R. Sharma, B. J. Braams, S. Carter, B. C. Shepler, and J. M. Bowman, J. Chem. Phys. 130, 174301 (2009)]. For all three bands, a-type and b-type transitions are observed from the lowest symmetry allowed roconvibrational state of each nuclear spin isomer, which allows for a determination of the tunneling splittings in both the ground and excited vibrational levels. Comparisons to gas phase millimeter-wave rotation-tunneling [K. Tanaka, M. Toshimitsu, K. Harada, and T. Tanaka, J. Chem. Phys. 120, 3604-3618 (2004)] and high-resolution jet-cooled infrared spectra [F. Dong, M. Roberts, and D. J. Nesbitt, J. Chem. Phys. 128, 044305 (2008)] reveal that the He solvent effect is to reduce the ground and ν3 excited state tunneling splittings by ≈20%. This solvent-induced modification of the tunneling dynamics can be reasonably accounted for by assuming either a ≈2.5% increase in the effective barrier height along the tunneling coordinate or a ≈5% increase in the effective reduced mass of the tunneling particles.
authors: Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA.
authors: Paul L
authors: PL
authors: Raston
authors: Tao
authors: T
authors: Liang
authors: Gary E
authors: GE
authors: Douberly