Splitting of e2g ground state fundamentals in D2h deuterium benzenes. Tests of benzene force fields
✍ Scribed by Lionel Goodman; Yoshinori Nibu
- Publisher
- Elsevier Science
- Year
- 1988
- Tongue
- English
- Weight
- 686 KB
- Volume
- 143
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
We report supersonic jet multiphoton ionization (resonant to the 'Bz. state) measurements of the ground state fundamental frequencies for eZg vibrations 6 and 8 in 13CgHb, and in para-C,H,D*, and para-C,H,D, where 6a and 6b, and 8a and 8b are not degenerate. The splittings for para-CaH4Dz are Iw~~-o~,,~ =6.6+0.3, and Iog,--ogbl =2.9+0.3 cm-'; for para-C6H2D4, Io~~--w& ~3.9kO.3, and Io~~-w~~I =8.1 kO.5 cm-'. Comparison of the measured and predicted vibrational energy separations for various force fields shows that only comp/etcforcejefdr (no interactive force constants neglected) can even qualitatively reproduce these splittings. Accurate reproduction of 6a-6b energy splittings by the recent Ozkabak-Goodman complete harmonic force field suggests a mechanism for Rosman and Rice's recent observations that in the 'B2" excited state the higher lying component of the split 6a,b vibrational level has the longer lifetime and that the lifetime difference is correlated with the splitting energy. The lifetime difference is mainly due to kinematic effects arising from harmonic features in the 'B,, potential surface.