Experiments concerning the laser-enhanced reaction between vibrationally excited O3 and NO

Abstract
The reaction of vibrationally excited O3 with NO has been studied for the temperature range 138–410 ° K. Observations were made of chemiluminescence of vibrationally excited NO2(2A1) and electronically excited NO*2(2B1,2) reaction products immediately following laser excitation of O3(001) molecules. The present results, combined with previous rate constant measurements, permit a determination of the separate rates for formation of NO2(2A1) molecules and collisional deactivation of vibrationally excited O3 by NO. This latter rate constant exhibits a minimum value at 230 °K. It is shown that the stretching and bending modes of O3 make comparable contributions to reaction rate enhancement. Excitation of either the coupled stretching modes or the bending mode results in a lowering of the activation energies for reactions leading to NO*2(2B1,2) and NO2(2A1) products of 31% (1.3 kcal/mole) and 56% (1.3 kcal/mole), respectively. The intermode coupling of vibrational energy from the stretching modes to the bending mode of O3 in collisions with NO occurs with a rate constant of (1.2±0.6) ×104 sec−1 Torr−1 at 308±3 °K.