Flash spectroscopy with 2288 Å and 3261 Å cadmium resonance radiation. Part 1.—An experimental technique with a multi-electrode flash-lamp and some preliminary results

Abstract

A technique for the spectroscopic study of transient species in Cd-photosensitized reactions was described, in which intense flashes of the 2288 and 3261 Å resonance radiations were produced in a multi-electrode flash-lamp and absorbed in a coaxial reaction vessel of small diameter. Production of Cd(5³P) in the deactivation of Cd(5¹P₁) was demonstrated in He, N₂ and CH₄, and it was also suggested that H₂ deactivates Cd(5¹P₁)→Cd(5³P) prior to formation of CdH; the rate coefficient for the H₂ deactivation was estimated as 3 × 10^–10 cm³ molecules^–1 s^–1. Relative rates of formation of cadmium hydrides were correlated with reaction endothermicities and it was suggested that the processes occur adiabatically on a triplet potential energy surface. The rate coefficient of the thermal decomposition CdH + H₂→Cd(5¹S₀)+ H + H₂ was estimated as 3.3 × 10^–16 cm³ molecule^–1 s^–1 at 453 K. It was suggested that the rotational energy of the reactants contributes towards bond rupture. The wavelengths of the P heads of the bands of two new systems of CdH and CdD were reported.