7169in the matrix is increased; the probability of having two substitutional sites about any particular atom in the matrix having dopant species becomes 0.1 at -5 mol % of dopant from purely statistical considerations.'* Given the propensity of NO2 toward self-association, this concentration estimate may be high. The required proximity of all three ions virtually ensures that there will be some interaction between the two NO2-ions which would in turn perturb their infrared absorptions substantially. TOO, the simple estimate of the interionic distance is based on an additive Coulombic potential point charges, and neglects repulsion, shielding, structural effects, polarizabilities, etc.ies Cu+(N02-)(N02) requires an interionic distance of 2.64 r a n d since only two ions are involved we feel that it is much more probable than the first two possibilities. At high matrix concentrations of NO2, there is a relatively high possibility of a simple perturbation of the &+NO; moiety by a neighboring NO,. The infrared absorptions at 1214 cm-l can be assigned to the asymmetric N-O uj stretch of the perturbed NO;; the absorptions at 1192 and 1173 cm-I would be the same absorption but shifted due to structural isomerism of the NO2 units or due to matrix effects.Acknowledgment. (12) Pikaev, A. K.; Kabakchi, S. A.; Zansdrhova, A. A. Furaday Discuss. (13) Anderson, R. F.; Vojnovic, B.; Michael, B. D. Radial. Phys. Chem. (14) Hu, H.; Schuler, R. H. To be published.Time-resolved diode laser infrared absorptionlgain spectroscopy was used to investigate vibrational energy disposal in H20 produced in the reaction of OH with cyclooctane. Penistant population inversions under multipleallision conditions were observed while probing transitions between the 0 0 0 1 0 , 0 1 0 2 0 , and 010-100 vibrational states of H20. An equilibrated rotational temperature was determined to be 500 f 200 K for typical reaction conditions.