The Master Equation for the Dissociation of a Dilute Diatomic Gas. VII. Vibration–Dissociation Coupling in an Expansion Nozzle

Abstract

Nous rapportons un calcul de H + H + M + H, + M (sans couplage V-V) aboutissant a la temperature, la densite, la vitesse et les populations de chaque niveau vibrationnel individuel, de 3900-1500 O K , complete avec une precision acceptable le long de la ligne zero pendant un court temps d'ordinateur.Nous constatons qu'en I'absence de couplage V-V, que les populations sont toujours monotones avec le nombre quantique vibrationnel, quoique apparaissent certaines distortions dans les distributions des populations vibrationnelles; il est toutefois possible de susciter des surpopulations absolues d'un Ctat vibrationnel par rapport a un autre en simulant des effets de couplage vibrationnel.A partir de ce calcul, nous concluons principalement que sous ces conditions (i) la constante de vitesse de recombinaison est la constante de vitesse de recombinaison phenomenologique normale; (ii) le temps de relaxation vibrationnel T , , , semble varier sur plusieurs ordres de grandeur, dependant de l'approximation utilisee pour definir la quantite d'energie vibrationnelle, mais si on utilise une mesure approprite de l'energie vibrationnelle, rVi, peut &tre relit la deuxieme valeur quantifiee de la matrice de relaxation et par consequent est le m&me que celui qui aurait &ti: trouve au moyen d'une rnesure dans des tubes de choc.

Dynamics of collisional dissociation: I 2 in Ar and Xe

“…I t is particularly useful in studies of inelastic scat tering in reactive systems. Much progress along these lines was reported recently (Labib, McElwain & Pritchard 1972;Dove & Jones 1971). Quantitative calcula tions, which can be meaningfully compared with experiments, are laborious, and have been applied only to H 2.…”

Toward a unified master-equation theory of thermal decomposition reactions: Analytic solution for diatomic dissociation

“…Thus, the sensitivity of the ortho-para-recombination rate ratio, both to temperature and to the states which are assumed to be important, is shown to be an artefact. There only remains the question now of why, as we noted above, the proper nonequilibrium rate is greater than the rate predicted by the orbiting resonance theory, in which it is assumed that certain key participating states (14,4) state omitted; III, the (11,13) state omitted; and IV, both the (14,4) and (11,13) states omitted. remain in equilibrium?…”

“…[i.e., (v,J) = (14,4); (14,5); (13,8); (12,11); (12,12); and (11.13) ], but the importance of two of these, i.e., (14,4) and (11.13) has been downplayed recently.68,73,76 Calculation of the total rate constants k^T and the ortho-para-recombination rate ratios is straightforward using eq 44 and 45. The results of these calculations are compared with those of the full nonequilibrium calculations using the same set of transition probabilities in Figure 6.…”

“…Figure6. (a) Orthoand para-recombination rate constants for hydrogen in helium as a function of temperature: (-) master equation calculation, eq 43; (---) orbiting resonance calculation using eq 45 with six quasi-bound states; (•••) orbiting resonance calculation using eq 45 with four quasibound states (omitting the(14,4) and(11,13) states); (o) ortho-recombination rate; (3p) para-recombination rate, scaled by a factor of three, (b) Total recombination rate for hydrogen in helium: (-) master equation calculation using eq 44 for the transition probabilities; (---) orbiting resonance calculation with six quasi-bound states and using the same transition probabilities; (-) orbiting resonance calculation of Whitlock et al68 using trajectory deactivation data with the same six quasi-bound slates.…”