Non-equilibrium kinetics of bimolecular reactions. Part 7: The puzzle of the H+O2 reaction

Vibrational relaxation of highly excited HO2 in collisions with O2

“…Such a mechanism may be justified on the basis of reasonably strong long range interactions, and invoking that an extensive energy exchange between the vibrational modes is required. Also interesting is the fact that such events obey roughly an exponential energy-gap law, a propensity in agreement with other vibrational relaxation processes [2,11,[33][34][35]. We further observe that, for a fixed translational energy, the shape of the energy-transfer distribution does not significantly change with the initial vibrational energy, while the amplitude of the multiquantum-transitions in deactivation increases with the internal energy content of the donor species.…”

What are the Implications of Nonequilibrium in the O+OH and O+HO2 Reactions?

“…[78] with v' 3 at the expense of v' = 7-9, while the populations of intermediate levels are left basically unchanged. Parenthetically, we observe that the probability of vibrational de-excitation via the inelastic process (31) follows approximately the exponential-energy-gap law [40] Àln[P(Dv')] = 3.545À0.436Dv', with the size of the vibrational quantum jump Dv' = v f 'Àv i ' varying with v i ': vibrational transitions involving one quantum jump for small values of v i ', multiquantum transitions more likely for large v i '. In turn, Figure 3 b shows that the rotational distribution maintains its initial two-temperature character, with a slight increase in the population of high rotational states.…”

“…A key premise is that vibrationally excited O 2 , OH, and HO 2 species should be abundant enough in the middle atmosphere. In fact, diatomic molecules such as O 2 near the dissociation limit are known to require 10 5 -10 6 collisions to deexcite in the presence of inert species, such as Ar atoms, [40] while reactions involving highly vibrationally excited diatomic molecules have been found [5,37,38] to have rate constants for reaction much larger than those of the corresponding relaxation processes. Moreover, both the photolysis of O 3 and the reaction H + O 3 !OH + O 2 [the major sources of O 2 (v) and OH(v) at such altitudes, respectively] occur significantly faster than vibrational relaxation.…”

Theoretical feasibility study of new high-efficiency continuous-wave lasers operating at electron transitions in the spectral regions from near ir to uv on the basis of unconventional mechanisms of forming the active gaseous media

“…The calculations show that, in principle, lasing is also possible at initial room temperature of the mixture (To ~ 300 K); however, in this case, the efficiency of energy conversion decreases by a factor of about 1.5-2. On the other hand, if the mixture is deeply cooled (To ~ 100 K), the rate of vibrational exchange in H2 becomes appreciably lower [74]; therefore, it is very difficult to attain inversion in the system at such low temperatures.…”