The Role of Excess Kinetic Energy in the Reactions of O(¹D) Atoms

Abstract

). The effect of the excess kinetic energy of O('D) atoms on their reactions with some gaseous compounds was investigated using two different experimental methods. O('D) atoms with maximum excess kinetic energies of 41 + 5 and 31 kcal/mol respectively, were produced by flash photolysis of N 2 0 (1800-2300 A) and by photolysis of N 2 0 at 2139 A, in the presence and absence of He which is a deactivator of kinetic energy. In the first method the competition between N 2 0 and one of CO,, Xe, CO, and N2 for O('D) atoms was measured and it was found that the relative rate constants kco2/kNZo, k~. / k~,~, kco/kNZo, and k N 2 / k~2~ are not affected by the excess kinetic energy of the O('D) atoms.In the second method the competition between neopentane and one of C 0 2 , Xe, CO, and NP for O('D) atoms was measured. The results of the second study were not entirely conclusive. However, they also indicate no effect or at best only a very small effect of excess kinetic energy.

Reaction of hydroxyl with fluoroethane. The extent of hydrogen abstraction from the .alpha. and .beta. positions

“…It was found that addition of helium, which thermalizes kinetically hot H atoms fairly efficiently, increased the value of a/(a + ß). The effect is apparent in Figure 2 in which a/(a + ß) is plotted against the reciprocal of the helium pressure and against the average kinetic energy, {E), with which the H atoms react, calculated as described in ref 19. Neither plot is linear, but in each case a smooth curve can be extrapolated to give a/(a + ß) = 0.880 at infinite pressure of helium, cr for completely thermalized H atoms.…”

Kinetic study of the reactions of the hydroxyl radical with ethane and propane

“…Ethane (99.96%) and propane (99.99%) were degassed prior to use. [6], using the flash photolysis-resonance absorption technique, measured kz(295 K) = (2.02 f 0.10) X cm3/molecule-s. This value is roughly twice that obtained in the present work, and the discrepancy is somewhat surprising in light of the good agreement between the two studies on kl(297 K).…”

Potential Energy Surface of the O(1D) + N2O → 2NO, O2 + N2 Reactions

“…The experimental studies of the reaction (2) are restricted mainly to the problem of the reaction branching values. 1,4,6,17 The final products of both reaction channels are ground state molecules. However, the direct formation of the triplet ground state oxygen molecule in reaction channel (2) is spin forbidden, as both reaction species are in a singlet state.…”

“…In the experimental studies of the reactions (1) and (2) the excited O( 1 D) atoms are mostly produced by UV photodissociation of the N 2 O molecules. − The free O( 1 D) atoms collide with the nondissociated N 2 O molecules and react with them with a near unit efficiency. , Most attention in the experimental studies has been paid to the reaction (1), − as the product of this reaction, NO, is a much easier object for spectroscopic analysis than the homonuclear O 2 and N 2 molecules, the reaction (2) products. The experimental studies of the reaction (2) are restricted mainly to the problem of the reaction branching values. ,,, …”