REASSIGNMENT OF THE $11537 cm^{-1}$ BAND OF HYDROGEN FLORIDE DIMER AND OBSERVATION OF THE INTERMOLECULAR COMBINATION MODE $3\nu_{1} + \nu_{4}$

Loading...
Thumbnail Image

Date

1997

Journal Title

Journal ISSN

Volume Title

Publisher

Ohio State University

Research Projects

Organizational Units

Journal Issue

Abstract

We report a high resolution re-examination of K=1 subband of 3ν2+ν4 and the 3ν1+ν1(K=0) combination mode of (HF)2 by intracavity laser induced fluorescence. The fluorescence is monitored with a germanium detector which collects only first overtone emission (2→0) of HF fragments. The band centered at 11537cm−1 is shown to be K=1 of 3ν2+ν6 [previously assigned to K=1 of ν1+2ν2, {J. Chem. Phys}. 100, 1 (1994)]. Hydrogen interchange tunneling is almost completely quenched (Δνt=0.6 GHz). Vibrational predissociation rate is rapid (4.5 GHz) but half that of 10GHz observed in 3ν2. The combination mode 3ν1+ν4 is recorded with band origins of 11402.889(4) and 11402.868(8)cm−1 and rotational constants of 0.21639(17) and 0.21704(15)cm−1 for the two tunneling components A+ and B+, respectively. The frequency of this intermolecular vibration, ν4, upon 3ν1 excitation is 129.36cm−1, quite similar to that at the fundamental, suggesting only a minor dependence of the hydrogen bond vibration on the free-HF bond length. The predissociation linewidth for 3ν1+ν4 mode is 2.5(2) GHz, which is one order of magnitude larger than the 0.24(2) GHz of the 3ν1 state. The coupling of this state to the dark state of 3ν2+ν4+ν5 is suggested for the origin of the observed linewidth increase.

Description

Author Institution: Department of Chemistry, Harvard University; Institute of Atomic and Molecular Sciences, Academica Sinica

Keywords

Citation