Vibrational relaxation of ortho and para-H2 in the range 400-50 K

Audibert, M.; Vilaseca, R.; Lukasik, J.; Ducuing, J.

doi:10.1016/0009-2614(75)85009-3

Cited by 71 publications

(36 citation statements)

References 13 publications

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“…A detailed dynamical investigation will probe a significantly larger area of the PES and test its validity by comparing with available experimental measurements. [5][6][7][8][9] Work in this direction is underway in our laboratory. It can also be modified to study reactive scattering, an important aspect of dynamics that has attracted some recent theoretical attention.…”

Section: Discussionmentioning

confidence: 99%

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Full-dimensional quantum wave packet study of rotationally inelastic transitions in H2+H2 collision

Lin

Guo

2002

The Journal of Chemical Physics

100

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We report full-dimensional accurate quantum dynamical calculations of the rotationally inelastic collision: para-H 2 ( 1 ϭ0,j 1 ϭ0)ϩpara-H 2 ( 2 ϭ0,j 2 ϭ0)→para-H 2 ( 1 ϭ0,j 1 Ј)ϩpara-H 2 ( 2 ϭ0,j 2 Ј), using a wave packet approach based on the Chebyshev polynomial expansion of Green's operator. The six-dimensional Hamiltonian within the coupled-states approximation is discretized in a mixed grid/basis representation and its action is computed in appropriate representations facilitated by a series of one-dimensional pseudo-spectral transformations. Both the parity and diatomic exchange symmetry are adapted. The S-matrix elements for the rotational transitions are obtained at all energies by the Fourier transform of Chebyshev correlation functions and used to compute transition probabilities, differential and integral cross sections, and state-resolved thermal rate constants. Results are compared for two recently proposed ab initio based potential energy surfaces and with previous quantum results.

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Section: Discussionmentioning

confidence: 99%

“…2 In order to model the kinetics and thermal balancing in these circumstances, accurate rovibrational transition rate constants are essential. For these reasons, there have been keen experimental [3][4][5][6][7][8][9] and theoretical 2,10-25 interests in elucidating state-to-state collision dynamics between hydrogen molecules.…”

Section: Introductionmentioning

confidence: 99%

Full-dimensional quantum wave packet study of rotationally inelastic transitions in H2+H2 collision

Lin

Guo

2002

The Journal of Chemical Physics

100

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“…dX (13) dz m 0 uj g c T /I dX 7 dA \ \ (1+x) dz~ A dz / (14) where (R is the rate of dissociation, given by …”

Section: Modeling Of the Recombination Zones And Nozzlementioning

confidence: 99%

Microwave Plasma Generation of Hydrogen Atoms for Rocket Propulsion

Chapman

Filpus

Morin

et al. 1982

Journal of Spacecraft and Rockets

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Hydrogen dissociation in a microwave plasma and recombination is under study for propulsion. The species and energy transport and reaction processes occurring in a microwave discharge are investigated. A general model of the reaction system has been developed which supports experiment design and data correlation. The energy efficiency of the dissociation-recombination cycle is considered. Models of the recombination process are being developed to include estimates of rotational and vibrational energies, the effect of molecular relaxation on thermal energy, and the effect of bulk kinetic energy of flow on total energy of reaction, so as to avoid thermal equilibrium limitations. It was found that system pressure is an important parameter. NomenclatureA = cross-sectional area for flow, m 2 a = rate constant parameter 1, kgmole ~2m 6 s~1T~6 b = rate constant parameter 2 (dimensionless) c = rate constant parameter 3 = (activation energy//?), K C p = heat capacity at constant pressure, J kgmole ~l K ~l E = electric field, Vm-1 F H2 = inlet hydrogen flow rate g c . = gravitational constant, m 2 s ~2 J ~l A// = heat of reaction, J kgmole ~1 k = rate constants K Qq = equilibrium constant, m 3 kgmole ~l m 0 = molecular weight of hydrogen, kg • kgmole ~] N A = Avogadro's number N = number density = PN A /RT,m~3 P = pressure, Pâ abs = power absorbed, W R =gas constant, 8314J kgmole ~l K -l (R = reaction rate, kgmole m ~3 s ~l T = temperature, K u b = bulk flow velocity, m s'~] V = volume of NOC1 reservoir, m 3 X = conversion z = distance down reactor, m [ ] = concentration of species, kgmole m ~3

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“…7,8 However, the number of experimental studies of relaxation phenomena in H 2 is limited. The vibrational energy relaxation vϭ1→0 has been measured by Kiefer and Lutz, 9 Audibert et al, 10,11 and Dove and Teitelbaum 12 ͓reaction rate k(vϭ1→0)ϳ10 Ϫ21 m 3 s Ϫ1 at 500 K͔. More recently Kreutz et al 13 measured the vibrational energy relaxation of the vϭ2 state.…”

Section: Introductionmentioning

confidence: 99%

“…For hydrogen, proven techniques are coherent anti-Stokes Raman scattering ͑CARS͒, 17,30 and the laser Schlieren technique. 9,11,12 Due to the relatively high detection limits these techniques are limited to the lower vibrational states and to the lower rotational levels of these lower vibrational states. Furthermore the spatial resolution, in the case of CARS, is often limited, even in BOXCARS mode, 30 in which a crossed-beam arrangement is used.…”

Section: Introductionmentioning

confidence: 99%

Relaxation behavior of rovibrationally excited H2 in a rarefied expansion

Vankan

Schram

Engeln

2004

The Journal of Chemical Physics

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The evolution of the rotational and vibrational distributions of molecular hydrogen in a hydrogen plasma expansion is measured using laser induced fluorescence in the vacuum-UV range. The evolution of the distributions along the expansion axis shows the relaxation of the molecular hydrogen from the high temperature in the upstream region to the low ambient temperature in the downstream region. During the relaxation, the vibrational distribution, which has been recorded up to vϭ6, is almost frozen in the expansion and resembles a Boltzmann distribution at T Ϸ2200 K. However, the rotational distributions, which have been recorded up to Jϭ17 in vϭ2 and up to Jϭ11 in vϭ3, cannot be described with a single Boltzmann distribution. In the course of the expansion, the lower rotational levels (JϽ5) adapt quickly to the ambient temperature (Ϸ500 K), while the distribution of the higher rotational levels (JϾ7) is measured to be frozen in the expansion at a temperature between 2000 and 2500 K. A model based on rotation-translation energy transfer is used to describe the evolution of the rotational distribution of vibrational level vϭ2 in the plasma expansion. The behavior of the low rotational levels (JϽ5) is described satisfactory. However, the densities of the higher rotational levels decay faster than predicted.

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Vibrational relaxation of ortho and para-H2 in the range 400-50 K

Cited by 71 publications

References 13 publications

Full-dimensional quantum wave packet study of rotationally inelastic transitions in H2+H2 collision

Full-dimensional quantum wave packet study of rotationally inelastic transitions in H2+H2 collision

Microwave Plasma Generation of Hydrogen Atoms for Rocket Propulsion

Relaxation behavior of rovibrationally excited H2 in a rarefied expansion

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