TEMPERATURE-DEPENDENCE OF THE RATE-CONSTANT AND BRANCHING RATIO FOR THE OH+CLO REACTION

The overall rate constant and branching ratio for the OH + ClO reactio n have been measured using the turbulent how technique with high-press ure chemical ionization mass spectrometry for the detection of reactan ts and products. At 298 K and ca. 100 Torr pressure, the overall rate constant was determined to be (1.46 +/- 0.23) x 10(-11) cm(3) molecule (-1) s(-1). The temperature dependence of the rate constant was invest igated between 205 and 298 K, yielding the following Arrhenius express ion: (5.5 +/- 1.6) x 10(-12) exp[(292 +/- 72)/T] cm(3) molecule(-1) s( -1). For the branching ratio studies OD was used instead of OH, making it possible to observe directly the production of DCl from the minor channel of the OD + ClO reaction. The temperature dependence of the ra te constant for this minor channel was investigated between 210 and 29 8 K, yielding the following Arrhenius expression: (1.7 +/- 0.3) x 10(- 13) exp[(363 +/- 50)/T] cm(3) molecule(-1) s(-1). The branching ratio for the DCl channel was found to range from 0.05 +/- 0.02 at 298 K to 0.06 +/- 0.02 at 210 K.