Bulletin of the Korean Chemical Society

Korean Chemical Society (대한화학회)
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Laser-Induced Fluorescence Excitation Spectrum and $CF_3$ Torsional Potential Energy Function of 7-Amino-4-(trifluoromethyl)coumarin in Its $S_1$ Electrode Excited State

  • Published : 1996.05.20
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Abstract

The laser-induced fluorescence excitation spectrum of 7-amino-4-(trifluoromethyl)coumarin in a supersonic jet has been recorded in the 340-352 nm region. The electronic band origin was observed at 28622.8 cm-1. Vibrational assignments for the three fundamental low-frequency modes and eight combination bands have been made for the S1 electronic excited state. The out-of-plane vibrations of this molecule have been characterized from the low-frequency assignments of the spectrum. The periodic potential energy function for the CF3 torsion, which satisfactorily fits the observed data, were also determined to be V(Φ)=95X(1-cos3Φ)-32X(1-cos6Φ) where Φ is the torsional angle. The relatively low torsional barrier of 99 cm-1 in S1 state could be explained by the small steric interactions between the functional groups attached to a bicyclic ring.

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References

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