RADICAL-MOLECULE KINETICS IN PULSED UNIFORM SUPERSONIC FLOWS - TERMOLECULAR ASSOCIATION OF OH PLUS NO BETWEEN 90-K AND 220-K

The low-temperature dependence of the termolecular association reactio n of OH with NO employing N-2 as the third body has been investigated using a new pulsed uniform supersonic expansion flow reactor. The abso lute low-pressure reaction rate coefficient is reported for the temper ature range 90-220 K. The temperature dependence of the rate coefficie nt for this reaction is found to be well fit by k = (7.0 +/- 2.0) x 10 (-31)(T/300)(-2.6+/-0.3) cm(6) s(-1). The results agree with those obt ained in the higher temperature regime and with RRKM predictions of th e rate coefficient both validating the new technique and providing val uable information on the extended temperature dependence of this atmos pherically relevant reaction.