Direct rate measurements on the reaction D + OH ? OD + H from 300 to 515 K

Rate constants for the reaction D + OH → OD + H (1), have been measured at temperatures from 300 to 515 K. The pseudo-first-order decay of OH radicals, generated by pulsed laser photolysis of HNO3 or H2O, was monitored by resonance fluorescence in the presence of a known excess concentration of D atoms produced by microwave discharge in the flowing gas mixture. The expression k1=(1.9 ± 0.3)× 10–9T–(0.63 ± 0.05) cm3 molecule–1 s–1, fitted the observed rate constants, yielding a value at 298 K (k1= 5.3 × 10–11 cm3 molecule–1 s–1) which is only 40% of the only other determination of this rate constant at room temperature.