Flash photolysis of iodides in the presence of quenching gases. I. Photolysis of C2F5I

A 'quenching buffer' method was developed for the determination of the rate constants of the principal reactions involved in flash photolysis of iodides (RI) in the ultraviolet part of the spectrum in the presence of a buffer gas M which acted as a strong quenching agent on the excited state 5²P_1/2 (I^*) of the iodine atom. The active iodine was in the form of C₂F₅I molecules, and the buffer consisted of CF₃H or H₂O molecules. The rate constants of the following reactions were obtained: C₂F₅+ C₂F₅ → C₄F₁₀, C₂F₅+I → C₂F₅I, I^* + (RI, M) → I+(RI, M), I + I +(RI, M) → I₂ +(RI, M). The coefficients γ, representing broadening of the active transition line of the photodissociation iodine laser by collisions with C₂F₅I, CF₃H, and H₂O molecules, were determined. The results demonstrated a correlation between γ and the constant representing quenching of I^* by the buffer M.