Predissociation of the c3Πu state of H2, populated after charge exchange of H2+ with several targets at keV energies

Bruijn, D. P. de; Neuteboom, J.; Los, J.

doi:10.1016/0301-0104(84)85035-1

Cited by 65 publications

(18 citation statements)

References 26 publications

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“…This process was simulated by using a model for the alkali density which was described by de Brujin et al [19]. This effect leads to measured lifetimes, which are longer than the true values, since in the region, where the decay is observed, new molecules are formed.…”

Section: A Methodsmentioning

confidence: 99%

Spectroscopy of triatomic hydrogen

Figger

Ketterle

Walther

1989

Z Phys D - Atoms, Molecules and Clusters

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The visible emission spectra of H3, D2 H, H2D and D 3 were studied. Triatomic hydrogen molecules were produced by neutralization of fast ion beams in alkali vapors. In addition to the well-known 0 -0 bands, weak vibrational bands of the electronic 3p z,,, "12 -' 2s 2A' 1 transition of D3 and DzH were observed and analyzed. F r o m the decay of the emission along the molecular beam lifetimes of excited states were obtained. For all observed states, 3 p 2A~, 3 s 2A] and 3 d, lifetimes strongly depend on the isotopic mixture. Many lifetimes measured were considerably shorter than ab initio predictions of the radiative lifetimes. Thus radiationless decay is important for all these excited states. Predissociation of the 3 p 2A~ state increases with the rotational quantum number. Possible decay channels are discussed.

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Section: A Methodsmentioning

confidence: 99%

Spectroscopy of triatomic hydrogen

Figger

Ketterle

Walther

1989

Z Phys D - Atoms, Molecules and Clusters

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“…1, the relevant interaction potentials are shown. When two H1s atoms approach on the repulsive b 3 u potential, transitions can occur to various vibrotational states of the c 3 u state [16][17][18]. The c 3 u state dissociates into H1s H2p.…”

Section: H-impact Excitationmentioning

confidence: 98%

“…Interaction potentials relevant to electronic excitation of H1s to H2p and radiation of the B-X and C-X bands [16][17][18][19][20].…”

Section: He-impact Excitationmentioning

confidence: 99%

“…Nomenclature A = reaction rate constant, cm 3 =s Ai; j = rate of radiative transition from state i to j, s 1 bc; i = free-bound radiative transition rate coefficient, = radiation intensity, W=cm 2 m sr i, j = principal quantum number or row or column number in matrix M K e i; j = rate coefficient for transition from state i to state j by electron impact, cm 3 =s K H i; j = rate coefficient for transition from state i to state j by H impact, cm 3 =s K He i; j = rate coefficient for transition from state i to state j by He impact, cm 3 =s K n i; j = effective rate coefficient for transition from state i to state j by H and He impacts, Eq. (17), cm 3 =s k = 1:3806 10 16 , Boltzmann constant, erg=K k fi = ith term in ionization rate coefficient expression, unit varies k ri = ith term in ionic recombination rate coefficient expression, unit varies N E i; T = hypothetical number density of state i in equilibrium with the free state at T, cm 3 N H = number density of hydrogen atoms, cm 3 N He = number density of helium atoms, cm 3 Ni = number density of state i, cm 3 N e = electron number density, cm 3 N n = N H N He , cm 3 N = hydrogen ion-number density, cm 3 p = pressure, atm or Torr Q = power gained by radiation, W=m 3 q r = radiative heat flux, W=cm 2 s = preexponential power in rate coefficient, dimensionless T = heavy particle translational-rotational temperature, K T a = TT v p T d = reaction temperature, K T v = vibrational-electron-electronic temperature, K U s = shock velocity, km=s W = rate of chemical production, mol=kg s x = distance from shock wave, cm x e = equilibration distance, cm = emission coefficient, W=cm 3 m sr = absorption coefficient, cm 1 = equivalent mass, g = collision or radiation frequency, s 1 = gas density, kg=m 3 i = Ni=N E i; T H = cross section for H-impact excitation of H, cm 2 He = cross section for He-impact excitation of H, cm 2 = time to equilibration, s Subscripts E = equilibrium e = electron v = vibration 1 Introduction H UMANS have succeeded in entering the atmosphere of the planet Jupiter in the Galileo Probe mission. But the other outer planets, Saturn, Uranus, and Neptune, are yet to be explored.…”

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confidence: 97%

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Nonequilibrium Ionization and Radiation in Hydrogen-Helium Mixtures

Park¹

2012

Journal of Thermophysics and Heat Transfer

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A theoretical model describing the nonequilibrium processes occurring behind a normal shock wave in a hydrogen-helium mixture is developed by assembling the latest information on physical properties and by comparing the calculation with the two sets of shock-tube data obtained in the 1970s. The cross-section value of 4 10 17 for electronic excitation of hydrogen atoms by the impacts of hydrogen and helium atoms derived earlier by Leibowitz is confirmed. The intensity of radiation in a nonequilibrium flow is typically twice that in an equilibrium flow. A sample calculation is made for an entry flight in the atmosphere of Neptune to show that the radiative heat load under nonequilibrium is more than twice that under equilibrium. Nomenclature A= reaction rate constant, cm 3 =s Ai; j = rate of radiative transition from state i to j, s 1 bc; i = free-bound radiative transition rate coefficient,average molecular speed, cm=s c = continuum (free, i.e., ionized) state Ei = energy level measured from the ground state of H, erg E v = vibrational-electron-electronic energy, J=kg E 1 = ionization potential of H, erg e = energy feedback factor f = Lyman-line escape factor, Eq. (48) H = flow enthalpy, J=kg H i = energy of ith reaction, J=mol h = Planck's constant I = radiation intensity, W=cm 2 m sr i, j = principal quantum number or row or column number in matrix M K e i; j = rate coefficient for transition from state i to state j by electron impact, cm 3 =s K H i; j = rate coefficient for transition from state i to state j by H impact, cm 3 =s K He i; j = rate coefficient for transition from state i to state j by He impact, cm 3 =s K n i; j = effective rate coefficient for transition from state i to state j by H and He impacts, Eq. (17), cm 3 =s k = 1:3806 10 16 , Boltzmann constant, erg=K k fi = ith term in ionization rate coefficient expression, unit varies k ri = ith term in ionic recombination rate coefficient expression, unit varies N E i; T = hypothetical number density of state i in equilibrium with the free state at T, cm 3 N H = number density of hydrogen atoms, cm 3 N He = number density of helium atoms, cm 3 Ni = number density of state i, cm 3 N e = electron number density, cm 3 N n = N H N He , cm 3 N = hydrogen ion-number density, cm 3 p = pressure, atm or Torr Q = power gained by radiation, W=m 3 q r = radiative heat flux, W=cm 2 s = preexponential power in rate coefficient, dimensionless T = heavy particle translational-rotational temperature, K T a = TT v p T d = reaction temperature, K T v = vibrational-electron-electronic temperature, K U s = shock velocity, km=s W = rate of chemical production, mol=kg s x = distance from shock wave, cm x e = equilibration distance, cm = emission coefficient, W=cm 3 m sr = absorption coefficient, cm 1 = equivalent mass, g = collision or radiation frequency, s 1 = gas density, kg=m 3 i = Ni=N E i; T H = cross section for H-impact excitation of H, cm 2 He = cross section for He-impact excitation of H, cm 2 = time to equilibration, s Subscripts E = equilibrium e = electron v =...

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“…Martin and Borondo (1988) calculated the lifetimes for the N=1 and 2 levels of the c u 3 P + (v=0-16) state of H 2 . De Bruijn et al (1984) also measured the predissociation lifetimes of several low (v, N) levels of c u 3 P + state through the accuracy of their measurement was probably over-estimated. The predissociation rates of the low N levels of the c u 3 P + (v=0) state were estimated by Chiu and Bhattacharyya (1979) and LaFleur and Chiu (1986).…”

Section: Introductionmentioning

confidence: 99%

Isotope dependence of thec³Π_u−b³Σ${}_{u}^{+}$ andD¹Π${}_{u}^{+}$−B′¹Σ${}_{u}^{+}$ predissociation rates of molecular hydrogen

et al. 2019

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The state-specific predissociation rates of the c u 3 P (v,N,J) state by b u 3 S + and the D u 1 P + (v,J) state by the B¢ u 1 S + continuum of various isotopologues of molecular hydrogen have been calculated from accurate ab initio potential energy curves and electronic coupling matrix elements. Lifetimes and predissociation rates of the c u 3 P (v,N,J) and D u 1 P + (v,J) levels and accurate energies of the c u 3 P -(v,N) and D u 1 P -(v,J) levels of the isotopologues have been obtained. Significant isotope dependence of state specific predissociation rate has been found even after adjustment for Franck-Condon factors and reduced mass. The use of average electronic matrix elements of H 2 for other isotopologues underestimates the c u 3 P + −b u 3 S + predissociation rates of the HD, HT, D 2 , DT and T 2 molecules by ∼12%, ∼16%, ∼30%, ∼40%, ∼52%, respectively, and the D u 1 P + −B¢ u 1 S + rates of the HD, HT, D 2 , DT and T 2 molecules by ∼10%, ∼15%, ∼26%, ∼35% and ∼45%, respectively. When compared at similar rotation, vibration and kinetic energies, the underestimation is nearly independent of the kinetic energy. The absolute value of the average electronic coupling matrix element increases with the reduced mass while that of the vibrational overlap integral decreases with the reduced mass. This accidental substantial cancellation in the D u 1 P + −B¢ u 1 S + system is responsible for the experimental observation that the relative D u 1 P + predissociation rate of two isotopologues approximately equals the squared inverse reduced mass ratio. The origin and implications of the isotope dependence of the averaged electronic coupling matrix elements are discussed.

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Predissociation of the c3Πu state of H2, populated after charge exchange of H2+ with several targets at keV energies

Cited by 65 publications

References 26 publications

Spectroscopy of triatomic hydrogen

Spectroscopy of triatomic hydrogen

Nonequilibrium Ionization and Radiation in Hydrogen-Helium Mixtures

Isotope dependence of thec³Π_u−b³Σ${}_{u}^{+}$ andD¹Π${}_{u}^{+}$−B′¹Σ${}_{u}^{+}$ predissociation rates of molecular hydrogen

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Predissociation of the c3Πu state of H2, populated after charge exchange of H2+ with several targets at keV energies

Cited by 65 publications

References 26 publications

Spectroscopy of triatomic hydrogen

Spectroscopy of triatomic hydrogen

Nonequilibrium Ionization and Radiation in Hydrogen-Helium Mixtures

Isotope dependence of thec3Πu−b3Σ${}_{u}^{+}$ andD1Π${}_{u}^{+}$−B′1Σ${}_{u}^{+}$ predissociation rates of molecular hydrogen

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Isotope dependence of thec³Π_u−b³Σ${}_{u}^{+}$ andD¹Π${}_{u}^{+}$−B′¹Σ${}_{u}^{+}$ predissociation rates of molecular hydrogen