Renner--Teller effect on the highly excited bending levels of {ital {tilde a}} {sup 1}{ital A}{sub 1} CH{sub 2}
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 (United States)
The effect of Renner--Teller coupling between the {ital {tilde a}} {sup 1}{ital A}{sub 1} and {ital {tilde b}} {sup 1}{ital B}{sub 1} states of CH{sub 2} on the rotational structure of the {ital {tilde a}} {sup 1}{ital A}{sub 1} bending vibrational levels has been observed. Renner--Teller coupling causes a decrease in the {ital A} rotational constant of the {ital {tilde a}} {sup 1}{ital A}{sub 1} (0,5,0) level, at 6400 cm{sup {minus}1} above the zero-point level, compared to the value extrapolated from the (0,{ital v}{sub 2},0) {ital v}{sub 2}=0--4 levels. Excellent agreement is obtained between the experimentally determined {ital A} value for (0,5,0) and that predicted by {ital ab} {ital initio} calculations of Green {ital et} {ital al}. [J. Chem. Phys. {bold 94}, 118 (1991)]. The effect of Renner--Teller coupling on the {ital A} rotational constant of bending levels as low as {ital v}{sub 2}=3 has also been detected. The barrier height to linearity in the {ital {tilde a}} {sup 1}{ital A}{sub 1} state was also estimated by fitting the {ital {tilde a}} {sup 1}{ital A}{sub 1} bending level term values to a harmonic plus Gaussian perturbation potential function, where the effects of orbital angular momentum were explicitly included to account for electronic-rotational coupling in the calculation. The value of 8600{plus_minus}400 cm{sup {minus}1} obtained is in good agreement with the {ital ab} {ital initio} result of 8800 cm{sup {minus}1}.
- DOE Contract Number:
- FG02-86ER13584
- OSTI ID:
- 29292
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 17 Vol. 102; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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