Kinetics of the NCS Radical

The reaction kinetics of NCS radicals with several molecules was investigated for the first time, using laser-induced fluorescence spectroscopy to measure total rate constants and infrared absorption spectroscopy to probe possible reaction products. The NCS + NO reaction has a pressure-dependent total rate constant, with a low pressure (∼2 Torr) rate given by the expression k NCS + NO = (4.1 ± 1.4) × 10 -15 exp[(1561 ± 116)/ T ] cm 3 molecule -1 s -1 over the range 298−468 K. On the basis of the observed pressure dependence and product detection studies, this reaction is believed to be an association reaction, producing primarily NCSNO products. The NCS + NO 2 reaction was pressure-independent, with a rate constant given by k NCS + NO 2 = (7.0 ± 0.6) × 10 -12 exp[(579 ± 39.4)/ T ] cm 3 molecule -1 s -1 over the range 298−620 K. No reaction of NCS with C 2 H 2 or O 2 was detected, and upper limits of rate constants with these molecules were estimated at <1.0 × 10 -14 cm 3 molecule -1 s -1 .