The formation and detection of some low-lying excited electronic states of BrCl and other halogens

Forty-nine bands arising from have been detected in the emission spectrum of from two sources: (i) the reaction of Br or Br2 with ClO2, in which is populated in the transfer reaction, 3 and (ii) the radiative combination of bromine and chlorine atoms, 5 The populations of the higher levels of formed in reaction (3) are less than in reaction (5). In reaction (3), is evidently formed via a triangular transition state similar to that postulated previously; the rate constant, k3, was found to be The combination of ground state iodine , and chlorine atoms was also found to be chemiluminescent in the red and near infrared region, and fifty-seven bands of the system , with , have been recorded. The radiative combination of ground-state chlorine atoms has been reinvestigated, and transitions of from v' ≼ 14 have been detected. Combining band head analyses of these emission spectra with previous data, the following constants (in cm-1) are reported: The reasons for the predominant radiation, during atom combination processes, from type states for Cl2 and BrCl, and from the 3II1 state for ICl, are discussed in relation to Brown & Gibson’s (1932) finding of a maximum in the potential energy curve of leading to and as dissociation products.