Rate measurements for the reactions H + I2→ HI + I and H + HI → H2+ I by Lyman‐α‐fluorescence

Rate constants for the reactions of hydrogen atoms with I2(k1) and HI(k2) have been determined in a discharge flow system using the detection of H‐atoms by Lyman‐α resonance fluorescence. Temperature dependent measurements in the range 250–420 K for H + I2show an extremely weak variation with temperaturek1,(H + I2) = (6.6 ± 3) 10−10exp(‐20 K/T) cm3/molecule · s. which is equally well represented by the temperature independent expressionk1, = (6 ± 2.5) 10−10cm3/molecule · s. — From rate measurements for H + HI in the range 250–370 K the Arrhenius expressionk2(H + HI) = (7.4 ± 2.0) 10−11exp(‐290 K/T) cm3/molecule · s is obtained.