Rotational and Torsional Analysis of the OH-Stretch Third Overtone in 13CH3OH

✍ Scribed by A. Chirokolava; David S. Perry; O.V. Boyarkin; M. Schmid; T.R. Rizzo

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 203 KB
• Volume: 211
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.2001.8506

✦ Synopsis

We record double resonance spectra of the 4ν 1 band of jet-cooled 13 C-methanol using single rotational state selection in the ν 1 fundamental and subsequent promotion of the selected molecules to the fourth vibrational level. We then detect transitions to the final excited states by infrared laser assisted photofragment spectroscopy (IRLAPS). The assigned A symmetry transitions reach upper states with K = 0 and 1, and J from 0 to 5. For E symmetry, the transitions reach levels with K in the range -3 to 2 and J from 1 to 7. The rotation-torsional analysis determines a value for the torsional tunneling splitting of 2.8 ± 0.4 cm -1 at v 1 = 4. In a previous paper (J. Chem. Phys. 110, 11 359-11 367 (1999)), we reported a trend of monotonically decreasing tunneling splittings in 12 CH 3 OH for v 1 = 0, 3, and 6 that we explained by a model that incorporates a linear increase in the torsional barrier height with OH stretch excitation. The 13 CH 3 OH tunneling splitting for the 4ν 1 band is in quantitative agreement with the trend found for 12 CH 3 OH.