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

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:456888

Xu, Li-Hong; Fraser, G T ^[1]; Andrews, A M ^[2]

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1. National Institute of Standards and Technology, Gaithersburg, MD (United States)
2. Institute for Defense Analyses, Alexandria, VA (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 K = 1 and 2, A symmetry, and the K= 2, E{sub 2} symmetry species. In the A torsional symmetry case, radiofrequency-infrared multiple resonance was used to obtain accurate asymmetry splitting for the v{sub co} = 1 and 2, C-O stretching states. The asymmetry splitting constants have been 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-two change in the K = 2 asymmetry splitting constant for the v{sub CO} = 2 level compared to the 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 v{sub co} = 2 torsional barrier height is found to be 372.227(3) cm{sup -1} or 374.984(7) cm{sup -1} depending on data set used. In the analysis the overtone vibrational energy origin is constrained to 2054.83113 cm{sup -1}. This barrier can be compared to the v{sub co} = 0 and 1 values of 373.5421 cm{sup -1} and 392.35 cm{sup -1}, respectively.

• OSTI ID: 456888
• Report Number(s): CONF-9506113--
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
HAMILTONIAN FUNCTION
METHANOL
VIBRATIONAL STATES