ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Two microwave-sideband CO2 lasers have been used with a molecular-beam electric-resonance spectrometer to study the overtone C–O stretching vibration of methanol. Infrared-infrared double-resonance results have been obtained for levels involving the K=1 and 2, A symmetry, and the K=2, E2 symmetry species. In the A torsional symmetry case, radio frequency-infrared multiple resonance was used to obtain accurate asymmetry splittings for the vco=1 and 2, C–O stretching states. The asymmetry splitting constants determined for these states are in good agreement with the literature values for the first excited C–O stretching states. However, the nearly factor-of-2 change in the K=2 asymmetry splitting constant for the vco=2 level compared to the vco=0 and 1 level results suggests that this state is weakly perturbed. The overtone transition frequencies obtained in this work were combined with previous overtone Fourier-transform results in a global fit to a torsion–rotation Hamiltonian to refine the fundamental molecular constants for the second-excited C–O stretching state. The vco=2 torsional barrier height is found to be 372.227(3) or 374.984(7) cm−1 depending on data set used. In the analysis the overtone vibrational energy origin is constrained to 2054.831 13 cm−1. This barrier can be compared to the v0=0 and 1 values of 373.5421 and 392.35 cm−1, respectively. © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.469653
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