Time-dependent self-consistent perturbation theory and applications to molecules |
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| Authors: | DW Davies |
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| Institution: | Department of Chemistry , University of Birmingham , Birmingham, B15 2TT |
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| Abstract: | The two most intense bands of the 370 nm electronic band system of tropolone have been rotationally analysed. They are separated by 18·93 cm-1 and it has been shown that the high wavenumber band is the 0--0- (H1 1) transition in what is almost certainly the internal hydrogen-bonding vibration v H : the low wavenumber band is the 0+-0+ (00 0) transition. A rotational contour analysis of both bands shows that there is an intensity alternation in K a″ such that the ratio K a″ even : odd is 10 : 6 in the 0+-0+ band and 6 : 10 in the 0--0- band. The intensity alternation, the nearly equal intensities of the 0+-0+ and 0--0- bands, the separation of these two bands and the anharmonic behaviour of v H show that the separation of the 0+ and 0- levels is small in the ground electronic state (probably less than 50 cm-1) and is 18·93 cm-1 larger in the excited electronic state. The 0+-0+ and 0--0- bands are both type B showing that the electronic transition is à 1 B 2-X 1 A 1 and therefore π*-π rather than π*-n. The π*-n transition is probably shifted to high wavenumber by the internal hydrogen-bonding. |
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