Infrared spectra gallane

Hi) Most of the bands in the infrared spectrum of gallane vapor carry unmistakable signs of rotational structure no better example is provided than that of the two absorptions near 1980 cm" the appearance of which, as measured at moderately high resolution with the aid of a multiple reflection cell, is illustrated in Fig. 5. There are, it appears, two types of band. One type, exemplified by the band at 1976 cm S displays all the features characteristic of a parallel band of a highly prolate symmetric top molecule (see Section III.B.l). The other type has the attributes of a perpendicular band of such a molecule (as witness the band at 1993 cm in Fig. 5). 

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