Chemiluminescence of alkaline earth monohalides in the collisions of ground state Ca, Sr, and Ba atoms with Cl2, Br2, I2, ICl,, ICl, and IBr

Formation of electronically excited alkaline earth monohalides MX* in the reactions of ground state Ca, Sr, and Ba atoms with Cl2, Br2, I2, ICl, and IBr was studied in a beam-gas arrangement. The MX* spectra were observed for all the reactive systems with the exception of Ca, Sr + I2. The energy balance indicates that MX* can be formed in a single-collision exchange reaction; also the dependence of MX*-chemiluminescence intensity on halogen gas pressure is typical of a bimolecular process. The MX*-chemiluminescence cross sections and lower limits of photon yields are estimated.