ON THE EMISSION-SPECTRUM OF HFS

The microwave induced emission spectrum of gaseous HfS has been studied in the region 11000-21000 cm(-1). Six band systems, not previously observed, have been photographically recorded in grating spectrographs and rotationally analysed. Five of the transitions terminate on a common tower state, the X(1) Sigma state. The five upper states are in energy order the A(1) Sigma, (BII)-I-1, (DII)-I-1, E(1)II and F-1 Sigma states. The sixth system, located between the B-X and D-X systems, is perturbed and is identified as the sulphide counterpart to the hafnium oxide system called C. Also, the three analysed lowest vibrational levels 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 determined using the direct approach method. Only the most abundant isotopomer (HfS32)-S-180 is treated.