Laboratory observation of hot bands of H+3

Bawendi, Moungi G.; Rehfuss, B. D.; Oka, Takeshi

doi:10.1063/1.458989

Cited by 93 publications

(48 citation statements)

References 34 publications

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“…The slowly-quenched ions are probably those in the v 1 =1 level. A similar conclusion was reached by Bawendi et al [37] who studied the absorption of H 3 + hot bands in He/H 2 discharges. This suggests that only H 3 + (v 1 =1) ions survive long enough to undergo recombination.…”

Section: Ion-formation and Vibrational Excitationsupporting

confidence: 62%

A critical review of H₃⁺recombination studies

Johnsen¹

2005

J. Phys.: Conf. Ser.

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After more that 30 years of experimental and theoretical work it now appears that theory and experiment on H 3 + recombination have finally converged. Since the storage ring results come very close to the latest theoretical calculations one might conclude that "the case is closed". However, some troublesome issues remain and should not be dismissed too quickly. For instance, some afterglow measurements showed faster decays at early afterglow times. It is now clear that the fast recombining species cannot be vibrationally excited ions since the same rates were found for spectroscopically identified H 3 + ions in v=0. On the other hand, there is no convincing explanation for the very small rates obtained in the Prague experiments at low H 2 densities. It is also puzzling that some measurements find nearly the same recombination coefficients for H 3 + and D 3 + , while others indicate that H 3 + recombines much faster. It has often been stated that vibrational excitation of the H 3 + ions tends to enhance recombination, but the evidence for that is far from solid; some observations suggest that the opposite is just as likely. IntroductionThe history of recombination studies of the H 3 + ion still presents a confusing picture, even to someone who has worked on experimental studies of this ion for more than 30 years and has closely followed the "ups and downs" of experimental results and the interplay between experiment and theory. It is most gratifying that we are now at the point where the best available theory [1, 2] agrees rather well with the latest results of ion-storage-ring experiments [3]. Has the time come to close the books and to say that no further work is needed? I do not think so.If one looks at the experimental results that were obtained over the years (see table 1 and table 2), one notices that the published thermal rate coefficients at temperatures near 300 K have varied by more than one order of magnitude. What shall we make of this large variation? Discarding the older data as "flawed" is not acceptable and may deprive us of useful insights. The variations do not seem to due to ordinary experimental errors such as calibration errors of probes etc. Almost all experimenters also studied the "benchmark ion" O 2 + to test their procedures and in that case the 300 K rate coefficients agree rather well (see e.g. the references to O 2 + data in [4] and [5]). It is far more likely that the poorly controlled and usually unknown internal energy of the H 3 + ion (vibrational, rotational) had an effect on the measured recombination rate. Of course, the vibrational energy of the "benchmark" O 2 + ions also was generally poorly controlled, but fortunately it seems to have only a small effect on the total recombination rate [6] and hence did not lead to significant discrepancies between results.

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Section: Ion-formation and Vibrational Excitationsupporting

confidence: 62%

A critical review of H₃⁺recombination studies

Johnsen¹

2005

J. Phys.: Conf. Ser.

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“…A difference-frequency laser spectrometer (36,37) was used to scan in the 3-m infrared region. Briefly, continuously tunable infrared radiation (ϳ200 W) was generated from a LiNbO 3 crystal, through which two orthogonally polarized visible beams from an Ar ϩ laser (ϳ1 W) and a tunable ring dye laser (ϳ1 W) passed collinearly.…”

Section: Methodsmentioning

confidence: 99%

Infrared Spectroscopy of H3O+: The ν1 Fundamental Band

Tang

Oka

1999

Journal of Molecular Spectroscopy

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“…Moreover, the use of symmetry adapted functions and hyperspherical coordinates yields a simple and nearly automatic procedure to assign the energy levels, almost always in good agreement with the previous assignment. 48 Finally, in Table IX, the deviation of the present results with respect to some experimental transitions 41,43,44,46,71,72,73 is shown and compared to that obtained using the levels of Dinelli et al 48 The typical error of the present GPES is of the order of tenths of cm Ϫ1 . These are larger errors than those obtained by Dinelli et al 48 Nevertheless, it should be noted that in the present potential, of global nature, adiabatic corrections have not been included.…”

Section: ͑17͒mentioning

confidence: 99%

Potential energy surface and wave packet calculations on the Li+HF→LiF+H reaction

Aguado

Paniagua

Lara

et al. 1997

The Journal of Chemical Physics

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Adiabatic global potential energy surfaces, for singlet and triplet states of AЈ and AЉ symmetries, were computed for an extensive grid for a total of 8469 conformations of H 3 ϩ system at full configuration interaction ab initio level and using an extended basis set that has also been optimized for excited states. An accurate ͑root-mean-square error lower than 20 cm Ϫ1 ) global fit to the ground-state potential is obtained using a diatomics-in-molecules approach corrected by several symmetrized three-body terms with a total of 96 linear parameters and 3 nonlinear parameters. This produces an accurate global potential which represents all aspects of ground-state H 3 ϩ including the absolute minimum, the avoided crossing and dissociation limits, satisfying the correct symmetry properties of the system. The rovibrational eigenstates have been calculated up to total angular momentum Jϭ20 using hyperspherical coordinates with symmetry adapted basis functions. The infrared spectra thus reproduced is within 1 cm Ϫ1 with respect to the experimental values for several transitions.

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Laboratory observation of hot bands of H+3

Cited by 93 publications

References 34 publications

A critical review of H₃⁺recombination studies

A critical review of H₃⁺recombination studies

Infrared Spectroscopy of H3O+: The ν1 Fundamental Band

Potential energy surface and wave packet calculations on the Li+HF→LiF+H reaction

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Laboratory observation of hot bands of H+3

Cited by 93 publications

References 34 publications

A critical review of H3+recombination studies

A critical review of H3+recombination studies

Infrared Spectroscopy of H3O+: The ν1 Fundamental Band

Potential energy surface and wave packet calculations on the Li+HF→LiF+H reaction

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Product

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A critical review of H₃⁺recombination studies

A critical review of H₃⁺recombination studies