25601-01-8Relevant academic research and scientific papers
Rate constants and vibrational energy disposal for reaction of H atoms with Br2, SF5Br, PBr3, SF5, and SF4
Malins, R. J.,Setser, D. W.
, p. 5666 - 5680 (1980)
Rate constants and initial HBr and HF product distributions for the title reactions were measured in a fastflow apparatus using infrared chemiluminescence techniques.The spectra were interpreted using a new set of Einstein coefficients for HBr, which are listed in the Appendix.The rate constants for HBr(υ>/=1) and HF(υ>/=1) formation, relative to the H+Cl2 reaction, are 3.3, 0.39, 0.50, 3.4, and 0.003, for Br2, SF5Br, PBr3, SF5, and SF4, respectively.This directly measured Br2 rate constant supports the smaller values that heve been estimeted in the literature.The initial HBr vibrational distribution (υ1:υ2:υ3:υ5=0.03:0.20:0.40:0.31:0.06) from H+Br2 corresponds to V>=0.49.The observed HBr vibrational distributions (υ1:υ2:υ3:υ4) are 0.28:0.43:0.23:0.06 and 0.63:0.24:0.13 for SF5Br and PBr3, respectively.The SF5Br results are close to the initial distribution and give V>=0.36.The low vapor pressure of PBr3 limited the and high was required to observe HBr emission; correcting the observed distribution for vibrational relaxation gives V ca. 0.47.These V > values include estimates for HBr(υ=0).Based upon the highest HBr level observed from SF5Br and PBr3, D0(Br-SF5)0(Br-PBr2)-1.The HF vibrational distributions from SF5 and SF4 decline with increasing υ, which suggests that these reactions proceed via a long-lived complex.For these cases the formation of HF(υ=0) is important, and significant corrwections must be made to the HF(υ>/=1) formation constants to obtain the total HF formation rate constants.The rate constants and energy disposal data are used to discuss models and compare the H+Br2 reaction to H+Cl2 and F2.
