ON THE EMISSION-SPECTRUM OF HFS

The microwave induced emission spectrum of gaseous HfS has been studie d in the region 11000-21000 cm(-1). Six band systems, not previously o bserved, have been photographically recorded in grating spectrographs and rotationally analysed. Five of the transitions terminate on a comm on tower state, the X(1) Sigma state. The five upper states are in ene rgy order the A(1) Sigma, (BII)-I-1, (DII)-I-1, E(1)II and F-1 Sigma s tates. The sixth system, located between the B-X and D-X systems, is p erturbed and is identified as the sulphide counterpart to the hafnium oxide system called C. Also, the three analysed lowest vibrational lev els of the F-1 Sigma state are perturbed. Accurate molecular constants of the five regular states, the X, A, B, D, and E states, have been d etermined using the direct approach method. Only the most abundant iso topomer (HfS32)-S-180 is treated.