Rate Constants for Reactions D * D2O -> D2 * OD by the Flash Photolysis-Shock Tube Technique over the Temperature Range 1285 - 2261 K: Results for the Back-Reaction and a Comparison to the Protonated Case

Article abstract of DOI:10.1021/j100369a048

The absolute rate constant for the reaction of D atoms with deuterium oxide, D + D2O -> D2 + OD, has been measured by using the flash photolysis-shock tube (FP-ST) technique.D atoms are monitored by atomic resonance absorption spectroscopy (ARAS) using Ly_αD lamp.The results, obtained over the temperature range 1285 - 2261 K, can be represented by the Arrhenius expression k = (2.90 +/- 0.73) * 1E-10 exp(-10815 +/- 356 K/T) cm³ molecule^-1 s^-1.The experimental results have been compared with results from the analogous protonated case, and an isotope effect of unity is indicated within experimental error.The rate constant for the back-reaction, OD + D2, calculated through the equilibrium constant, is k = (6.6 +/- 1.7) * 1E-11 exp(-3320 +/- 356 K/T) cm³ molecule^-1 s^-1, over the same temperature range, 1285 - 2261 K.Theoretical rate constants, based on a new potential energy surface by Kraka and Dunning, are calculated with conventional transition-state theory for both D + D2O and H + H2O.Similar calculations for both back-reactions are presented, and the theoretical calculations are compared to the experimental results.