HIGH-RESOLUTION STUDY OF THE 000-000-BAND OF THE (A)OVER-TILDE(1)A''-(X)OVER-TILDE(1)A' SYSTEM OF HNO IN EMISSION FROM THE H+NO REACTION

A high-resolution spectrum of the 000-000 band of the (A) over tilde ( 1)A ''-(X) over tilde (1)A' system of HNO has been recorded in emissio n from the reaction of the H atoms with NO. No sharp breaking-off in t he J structure has been found in the highest sub-band observed. The em ission in this sub-band (K-a' = 13-K-a '' = 12) originates in levels a bove the dissociation limit and arises from a two-body radiative assoc iation process. The emission in the other sub-bands originates in leve ls below the dissocation limit and arises from a three-body recombinat ion process. The mechanism for predissociation is discussed and an int erpretation has been given for a hitherto unexplained observation.