Study of the overtone C--O stretching band of methanol by multiple resonance spectroscopy

Journal Article · Sat Jul 01 04:00:00 EDT 1995 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.469653· OSTI ID:69047

Xu, L; Andrews, A M; Fraser, G T ^[1]

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1. Molecular Physics Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

Two microwave-sideband CO{sub 2} 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 {ital K}=1 and 2, {ital A} symmetry, and the {ital K}=2, {ital E}{sub 2} symmetry species. In the {ital A} torsional symmetry case, radio frequency-infrared multiple resonance was used to obtain accurate asymmetry splittings for the {ital v}{sub co}=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 {ital K}=2 asymmetry splitting constant for the {ital v}{sub co}=2 level compared to the {ital v}{sub co}=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 {ital v}{sub co}=2 torsional barrier height is found to be 372.227(3) or 374.984(7) cm{sup {minus}1} depending on data set used. In the analysis the overtone vibrational energy origin is constrained to 2054.831 13 cm{sup {minus}1}. This barrier can be compared to the {ital v}{sub 0}=0 and 1 values of 373.5421 and 392.35 cm{sup {minus}1}, respectively. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

• OSTI ID: 69047
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 1 Vol. 103; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
DOUBLE RESONANCE METHODS
INFRARED SPECTRA
METHANOL
MOLECULAR STRUCTURE
TORSION
VIBRATIONAL STATES