ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
By selecting a number of resonant A˜ 21 rotational lines in the optical–optical double resonance multiphoton ionization spectroscopy (OODR-MPI) of ammonia-d3, we have obtained rotationally resolved spectra of the ND3 B˜←A˜ 21←X˜ 00 transitions in the range of 550–730 nm, in which not only were we able to reanalyze rotationally the previously studied bands [J. Opt. Soc. Am. B 7, 1884(1990)], but also to assign rotationally and vibronically some novel spectra pertaining to the ν1, ν3, ν4, and ν3+ν4 excitations. Based on the symmetry assignment and the relationship of the vibronic coupling level energies between the single and dual mode cases, we have found that the Jahn–Teller splitting of the ND3 B˜ state invokes a novel type of the Fermi resonance, the nonadiabatic Fermi resonance. By taking account of this Fermi resonance, the modified vibronic coupling parameters of the ν3 and ν4 modes were calculated to be λ3=0.047 and λ4=0.023, which agrees well with the previous theoretical expectation that the ammonia B˜ state is subject to a mild dynamic Jahn–Teller effect. At present, four pairs of the nonadiabatic Fermi resonance have been discovered among the ND3 nonadiabatic levels, which can be separated into two types—one with the same selection rules as a conventional Fermi resonance, i.e., B˜ 31(1/2)–B˜ 42(5/2), B˜ 11–B˜ 42(1/2), and B˜ 31(3/2)–B˜ 42(3/2), the last of which was studied quantitatively with a coupling parameter K=114, and the other with novel selection rules, i.e., B˜ 31(1/2)–B˜ 11.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.463611
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