Direct measurement of the C2H5C(O)O-2+NO reaction rate coefficient using chemical ionization mass spectrometry

The rate coefficient for the reaction of the peroxypropionyl radical (C2H5C (O)O-2) with NO was measured with a laminar flow reactor over the temperatu re range 226-406 K. The C2H5C(O)O-2 reactant was monitored with chemical io nization mass spectrometry. The measured rate coefficients are k(T) = (6.7 +/- 1.7) x 10(-12) exp{(340 + 80)/T) cm(3) molecule(-1) s(-1) and k(298 K) = (2.1 +/- 0.2) x 10(-11) cm(3) molecule(-1) s(-1). Our results are compara ble to recommended rate coefficients for the analogous CH3C(O)O-2 + NO reac tion. Heterogeneous effects, pressure dependence, and concentration gradien ts inside the flow reactor are examined. (C) 1999 John Wiley & Sons, Inc.