Electronic branching ratios in the chemiluminescent reactions of Ca(1S) and Ca∗(3P) with ICl and IBr

Chemiluminescence of calcium monohalides formed in the reactions of ground state Ca(1S) and metastable Ca∗(3P) atoms with ICl or IBr was studied in a beam-gas arrangement. Total collision and chemiluminescence cross sections were measured to estimate photon yields of electronic states of the products. For the (A2Π+B2Σ+) states, aggregate yields appear to be arithmetic averages of the values for proper homonuclear halogen targets and branching ratios are in agreement with prior expectations. The experiment gives lower limits of the dissociation energies: D0(CaBr) ⩾ 353 kJ/mol and D0(CaI) ⩾293 kJ/mol.