Infrared chemiluminescence from vibrationally excited H2O, HOD, and D2O molecules in the ranges 3200-3900 cm(-1) (O-H stretch) and 2400-2900 cm(-1) (O-D stretch) was observed from the reactions of OH and OD radicals with hydrogen and deuterium bromide in a fast flow reactor with 0.5-2 Torr of Ar carrier gas at 300 K. Hydroxyl radicals were produced via the H + NO2 reaction; the H atoms were generated by microwave discharge in a H-2/Ar mixture. Vibrational distributions for H2O, HOD, and D2O were determined by computer simulation of the experimental emission spectra. The H2O emission from OH + HBr reaction shows inverted populations for both the collisionally coupled stretching modes and the bending mode. Inversion in the bending distribution with a maximum for v(2) = 1 is more apparent in the v(1.3) = 1 level, which is populated up to the thermochemical limit of v(2) = 5. The HOD emission from OD + HBr shows an inverted population in the O-H stretching mode with a maximum for v(3) = 2 and shows a decreasing population in the collisionally mixed O-D stretching/bending v(1,2) levels with half the molecules in the v(1) = 0 group. The distribution in v(1,2) for HOD from the OH + DBr reaction also appeared to be decreasing for v(1) > 0 levels, but collisional redistribution to v(3) = 1 seems evident from the pressure dependence of the vibrational distributions. These distributions are discussed with the aid of the information theoretic analysis and compared to F atom abstraction reactions from HBr and DBr and to quantum-scattering calculations on an OH + HBr surface. The overall vibrational energy disposal is [f(v)] approximate to 0.6, which resembles the analogous three-body cases. However, the partitioning of the energy between stretching and bending modes raises new questions about reaction dynamics.
