The absolute intensity and quenching constants of the NO2 emission in the chemiluminescent reaction between nitric oxide and ozone have been determined using a large capacity-flow reactor at low pressures. These studies have confirmed the mechanism previously proposed :The rate constants of the primary steps are kl, = (7.6f1-5)x 1011 exp (-4180f300/RT) and klb= (4.3 f1.0) x 1011 exp (-2330f150/RT) cm3 mole-1 sec-1. The half-quenching pressures (k2/k3m) of electronically excited NO2 produced are : Ar = 13.03~ 1.0 p, 0 2 = 8-3f0.5 p, NO = 5.2f0.3 p, NO2 = 3.7f0-1 p. The detailed mechanism of reactions (la) and (lb) is discussed.

The combination–elimination reaction CH3 + CF3 → CH3CF3† → CH2CF2 + HF has been studied in a fast-flow system. Infrared chemiluminescence arising from the HF product has been observed from vibrational levels v = 1–4, and relative rate constants, k(v), have been obtained for HF formation in these levels. A study has also been made of the reaction CH2CF2 + Hg*(63P1) → CHCF + HF + Hg(61S0), which has been found to produce vibrationally-excited HF. Relative rate constants k(v) for vibrational levels v = 1–4 have been obtained. It appears that channelling of the potential energy into HF vibration, in the course of the elimination step, is more efficient in the first than in the second of these reactions. In the second reaction HF is eliminated with considerable rotational excitation.

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The angular distribution and velocity of SO reactively scattered from crossed molecular beams of oxygen atoms and CS2 have been measured. In c.m. coordinates, the SO is strongly forward scattered with an in plane angular distribution represented by exp(−θ/50°), indicating a direct reaction mechanism. The mean recoil velocity of SO is independent of the c.m. angle, showing that the average fraction of reaction exoergicity appearing as translational energy of product separation is <10%. Combined with other evidence on vibrational excitation of products, this suggests that the main channel for released energy is into rotation and that the reaction proceeds via highly bent intermediate configurations. The total reaction cross section is estimated to be 1.1 Å2.