ROTATIONALLY RESOLVED STRUCTURE IN THE FIFTH AND SIXTH TORSIONAL STATES OF ACETALDEHYDE: INTERNAL ROTATION ABOVE THE TORSIONAL BARRIER
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Date
2002
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Publisher
Ohio State University
Abstract
Fluorescence excitation spectrum of acetaldehyde in its transition $\tilde{A}^{1}A^{\prime\prime}-\tilde{X}^{1}A^{\prime}$ is analyzed for the torsional states exceeding the barrier. States with torsional vibrational quantum number $v_{t} = 5 A + E$ and 6 A at term energy $660-927 cm^{-1}$ are assigned. This region is about $100-340 cm^{-1}$ above the top of torsional barrier. These states lie between limits of the torsional vibrational motion and a free rotor; the states 5A and 6A lie close to mix and the K states in E sublevel split further. Avoided crossings for $\Delta K = 0$ and $\Delta m = 0$ mod 3 states are observed between $K = 2$ of $14^{0+}15^{4}$ and $14^{0+}15^{5}$ and of $14^{0-} 15^{4}$ and $14^{0-} 15^{5}$. Consequently the K structure of $14^{0+}15^{5}$ deviates significantly from the expected parabolic shape. Between the inversion doublets $14^{0+}$ and $14^{0-}$ the K structures and the K state at the lowest energy are quite different.
Description
Author Institution: Department of Chemistry, National Tsing Hua University; Institute of Atomic and Molecular Sciences, Academia Sinica