Time resolved vibrational chemiluminescence: Rate constants for the reactions F + HBr, HI → HF + Br, I and for the relaxation of HF(υ = 4) and HF(υ = 6) by HBr, HI, CO2, N2O, CO, N2 and O2

The reactions: F+HX(X=Cl, Br, I)→HF(υ⩽ υmax)+ X have been initiated by laser flash photolysis of F2 using the fourth harmonic output from a Nd:YAG laser. By analysing the time-dependence of high overtone vibrational chemiluminescence from HF(υ = υmax), rate constants have been determined at (295±4) K for these reactions and for collisional relaxation of HF(υmax). For X = Cl, Br and I, υmax = 3, 4 and 6, respectively. This paper reports rate constants for the reactions of F + HBr and F + HI: k2 = (6.2±0.5) × 10−11 cm3 molecule−1 s−1; k3 = (5.6∮.2+0.6 × 10−11 cm3 molecule−1 s−1 and for the relaxation of HF(υ = 4) and HF(υ = 6) by HBr, HI, CO2, N2O, CO, N2 and O2; kHBr4 = (2.2±0.2) × 10−11 cm3molecules−1 s−1; kHI6 = (2.0−0.5−0.4 × 10−10 cm3 molecule−1s−1; kCO2,4,kCO26 =(2.16±0.18) × 1O−11, (7.1±2.4) × 10−11 cm3 molecule −1 s−1, kN2O4,kN2O6 = (5.9±0.7) × 10−11, (1.2±0.4) × 10−10 cm3 molecule−1 s−1, kCO,4,kCO6 = (1.38±0.14) x 10−11, (4.1±1.3) × 10−11 cm3 molecule−1 s−1, kN24,kN26 = (3.5±0.4) × 10−13, (1.2±0.4) × 10−12, cm3 molecule−1 s−1, kO2,4,k O26 = (1.01 ±0.17) × 10−13,(2.7±1.1) × 10−13 cm3 molecule−1 s−1. These results are compared with those which we have obtained earlier for the F + HCl reaction and the relaxation of HF(υ = 3) and with the limited data obtained by other, mainly less direct, techniques.