Rotationally resolved structures in the fifth and sixth torsional states of A 1A'' acetaldehyde: Internal rotation above the torsional barrier

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Title:	Rotationally resolved structures in the fifth and sixth torsional states of A 1A'' acetaldehyde: Internal rotation above the torsional barrier
Authors:	Chou, Yung-Ching Huang, Cheng-Liang Chen, I-Chia Ni, Chi-Kung Kung, A. H. 周永慶倪其焜陳益佳
Contributors:	臺北市立教育大學自然科學系
Keywords:	EIGENVALUES EIGENVECTORS FLUORESCENCE LIBRATION ORGANIC COMPOUNDS ROTATIONAL SPECTRA ROTATIONAL STATES
Date:	2002
Issue Date:	2009-07-31 15:58:44 (UTC+8)
Abstract:	The fluorescence excitation spectrum of acetaldehyde in its transition A 1A''-X 1A' is analyzed for torsional states above the barrier. States with torsional vibrational quantum numbers vt=5A, 5E, and 6A at term energies 660-927 cm-1 are assigned. This region is 100-370 cm-1 above the torsional barrier. These states lie between the limits of torsional vibrational motion and free internal rotor motion, so that the close-lying 5A2 and 6A1 states mix for K>0, and K states in the E sublevel are widely split. From an analysis of calculated eigenfunctions, the composition of K=1 sublevels reaches nearly equal proportions of odd (A2) and even (A1) torsional wave functions when levels exceed the top of the torsional barrier, whereas the K=1 eigenfunctions of vt=4A1 lying near consists of mostly even (A1) functions. Avoided crossings with DeltaK=0 and Deltam=0 mod 3 selection rules are observed between K=2, E sublevels of 140+154 and 140+155 and between K=2, E sublevels of 140-154 and 140-155. The K energy-level structure of 140+155 deviates significantly from the expected parabolic shape. The K structures and the K state at the lowest energy differ appreciably for the two inversion doublets 140+ and 140-.
Relation:	The Journal of Chemical Physics, v.117(17), p.7906-7913
Appears in Collections:	[Department of Applied Physics and Chemistry] Periodical Articles

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