ASSIGNMENT OF THE 290-NM ELECTRONIC BAND SYSTEM OF INDAZOLE [1,2-BENZODIAZOLE] AS PI-ASTERISK-PI BY ROTATIONAL BAND CONTOUR ANALYSIS

The 000 band of the S1-S0 electronic absorption system of indazole at 290 nm has been analyzed, and the results of the computer simulation of its rotational contour have shown that this band is and A B hybrid with an intensity ratio A B = 1.22. The S1-S0 electronic system is assigned as A ̃1A′(ππ*)- X ̃1A′. The same result has already been reached for benzimidazole (E. Canéet al., J. Mol. Spectrosc.150, 222-228 (1991)), and other ring-condensed aza-aromatic compounds although the relative amount of the type B and A components is different in each band. The transition moment is in the molecular plane nearly equidistant from the a- and b-inertial axes (θ = ±42°). © 1992.