A calorimetric technique has been used to determine the rate constants of the reactions : H+H+M = H2+M, H+02+M = H02+M, in discharge flow experiments. The mechanism of the decay of hydrogen and of oxygen atoms under conditions when [HI -g [0]< [02], [MI is discussed.

The rate of decay of hydrogen atoms has been measured in a conventional type of discharge-flow system at temperatures between 190-350 OK. The recombination fitted the equation where Ic, is the first order surface rate constant. No three-body recombination for M = H was observed at the low levels of dissociation (2-5 %) employed. When the flow gases contained traces of water vapor and (or) oxygen as impurities, the homogeneous rate constants (k,,,) had a small positive activation energy which was due to the influence of a surface reaction between hydrogen atoms and the impurities.In the absence of impurities, true homogeneous rate constants were obtained. A value of k,,,, = 4.6 + 0.5 x 1015 cm6 mole-' s-' was found at 291 OK. The temperature variation was approximately T-'1' over the range 19G350 OK.

No abstract

No abstract

No abstract