Beam-gas study of chemiluminescent reactions of Sn, Ge, and Si with F2

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Abstract
Electronic chemiluminescence (CL) has been observed for the reactions of tin, germanium, and silicon with fluorine utilizing a beam-gas configuration. Only electronic states of the metal monofluorides which are energetically allowed in a single reactive collision of the metal atoms SnF(A 2Σ+), GeF(A 2Σ+), and SiF (A 2Σ+, a 4Σ−) have been observed, in contrast with the results of previous flame studies in which other high lying electronic states have been reported. Pressure and temperature variations of the CL indicate a first-order dependence with respect to metal and fluorine. Simulation of the A 2Σ+–X 2Π systems has been obtained by nonlinear least-squares fit of the experimental spectra. Vibrational populations of the A 2Σ+ states are found to be inverted, with the appearance of double maxima. Adiabatic correlation, with respect to overall electronic symmetries of the reactants and products, indicates all reactant surfaces lead to ground-state products. However, molecular orbital arguments indicate the presence of one diabatic surface connecting reactants and electronically excited products.