Dissociative electron attachment to hydrogen

Drexel, H.; Senn, G.; Fiegele, T.; Scheier, P.; Stamatovic, A.; Mason, Nigel J.; Märk, T.D.

doi:10.1088/0953-4075/34/8/307

Cited by 26 publications

(33 citation statements)

References 32 publications

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“…When our averaged DEA cross sections are conormalized to the data of [30] at the peak, their onset behavior below the peak is virtually identical to that of the data; TABLE I. Peak energies and values of cross sections for DEA to H 2 X 1 g ; v 0 0.…”

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confidence: 58%

“…The most recent and accurate measurement of nearthreshold DEA cross sections to H 2 X 1 g ; 0 are those of Drexel et al [30]. These authors performed experiments in two different high-resolution crossed-beam apparatuses: a hemispherical electron monochromator at a gas temperature of 300 K with a resolution of 100 meV [full width at half maximum (FWHM)], and a trochoidal monochromator at 400 K with FWHM of 200 meV.…”

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confidence: 99%

“…We have therefore extended the rotational frame transformation theory [33], which is widely used in studies of elastic and vibrationally inelastic scattering [34], to rearrangement collisions [35]. Horáček et al [7] and to data from the two experiments in [30]. All theoretical cross sections have been Boltzmann averaged and energy convoluted.…”

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confidence: 99%

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Importance of Nonresonant Scattering in Low-Energy Dissociative Electron Attachment to Molecular Hydrogen

Rabli

Morrison

2006

Phys. Rev. Lett.

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A central premise of nearly all theories of dissociative electron attachment is that this process is resonance driven. Neglect of nonresonant scattering, although appropriate for electron-molecule systems with narrow (long-lived) resonances, is problematic for the e-H2 system, which has one of the broadest known resonances. Using the nonadiabatic phase-matrix method we have found that at energies from threshold to 6 eV contributions from nonresonant scattering to cross sections to dissociative attachment to in its ground vibrational and electronic state exceed 60%. Comparison of theoretical and experimental cross sections argue strongly for further efforts to resolve the considerable remaining discrepancies over this most elementary rearrangement process.

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confidence: 58%

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Importance of Nonresonant Scattering in Low-Energy Dissociative Electron Attachment to Molecular Hydrogen

Rabli

Morrison

2006

Phys. Rev. Lett.

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“…Cross sections for these resonant processes, involving the ground electronic state of the H − 2 transient species, have been calculated and measured over decades, and large sets of data are now available for the applications [5][6][7][8][9][10]. More recently, the calculations have been extended to the DEA and RVE processes occurring through a Rydberg-excited resonant state of 2 + g symmetry, which is known to give rise to the so-called 14 eV resonance peak in dissociative attachment cross sections [8,11,12] and is also considered responsible for the structures with multiple peaks in the vibrational-excitation cross sections observed in electron-molecule collision experiments [13,14].…”

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confidence: 99%

Electron-impact vibrational excitation of vibrationally excited H2molecules involving the resonant2Σg+Rydberg-excited electronic state

et al. 2013

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Electron-impact theoretical cross sections and rate coefficients for vibrational excitation of vibrationally excited H 2 molecules, occurring through the H − 2 resonant species in the 2 + g Rydberg-excited electronic state, are presented. The cross sections are calculated as functions of the incident electron energy by adopting the local-complex-potential model for resonant collisions and by using ab initio calculated molecular potentials and resonance widths. The calculations have been extended to all possible vibrational transitions linking all 15 vibrational levels of the electronic ground state of the H 2 molecule. The corresponding rate coefficients are also obtained as a function of the electron temperature by assuming a Maxwellian electron energy distribution function, and a simple analytical expression is derived. Finally, the present rate coefficients for the transitions starting from the lowest vibrational level of the H 2 molecule are compared with those for the process involving the X 2 + u resonant state of the H − 2 molecular ion.

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“…Cluster ions can be observed with n extending well beyond 100. Crucially, only anions with odd n are seen, suggesting that these are produced by dissociative electron attachment to an H 2 or D 2 molecule, which is a well-known process in the gas phase [16][17][18]. Having formed H − , this can then combine with the other H 2 molecules in the cluster either by a three-body collision association [3] or via radiative association [4,19].…”

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Anionic Hydrogen Cluster Ions as a New Form of Condensed Hydrogen

et al. 2016

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We report the first experimental observation of negatively charged hydrogen and deuterium cluster ions, H − n and D − n , where n ≥ 5. These anions are formed by an electron addition to liquid helium nanodroplets doped with molecular hydrogen or deuterium. The ions are stable for at least the lifetime of the experiment, which is several tens of microseconds. Only anions with odd values of n are detected, and some specific ions show anomalously high abundances. The sizes of these "magic number" ions suggest an icosahedral framework of H 2 (D 2 ) molecules in solvent shells around a central H − (D − ) ion. The first three shells, which contain a total of 44 H 2 or D 2 molecules, appear to be solidlike, but thereafter a more liquidlike arrangement of the H 2 (D 2 ) molecules is adopted. to be strongly bent rather than linear. Consequently, there are real doubts about the basic structures of H − n ions that need to be resolved, and given that there are no reliable estimates of the actual dissociation energies (D 0 ) of these clusters, it is not even clear if anions with n > 3 are stable.Here we report the first experimental detection of anionic hydrogen and deuterium clusters larger than H − 3 =D − 3 and have done so for a wide range of cluster sizes. The experimental procedure involved the formation of the corresponding neutral ðH 2 Þ N and ðD 2 Þ N clusters by adding H 2 or D 2 gas to liquid helium nanodroplets. The neutral clusters were cooled to the ambient temperature of the helium nanodroplets, 0.38 K [13], prior to an impact by a beam of electrons with a controlled energy. H 2 and D 2 are heliophilic (have a negative chemical potential when immersed in liquid helium [13]) and so will reside inside the helium droplets rather than on the surface. The helium droplets were then exposed to a beam of electrons, which generated anionic products in the gas phase that were detected by mass spectrometry. The transfer of negative charge to the ðH 2 Þ n and ðD 2 Þ N clusters occurs via a mobile electron bubble, whose formation has a threshold energy in excess of 1 eV in order to inject the electron into the helium conduction band [14]. The droplets used in the present work were relatively large (∼10 6 helium atoms), and for droplets of this size the electron bubble, although

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Dissociative electron attachment to hydrogen

Cited by 26 publications

References 32 publications

Importance of Nonresonant Scattering in Low-Energy Dissociative Electron Attachment to Molecular Hydrogen

Importance of Nonresonant Scattering in Low-Energy Dissociative Electron Attachment to Molecular Hydrogen

Electron-impact vibrational excitation of vibrationally excited H2molecules involving the resonant2Σg+Rydberg-excited electronic state

Anionic Hydrogen Cluster Ions as a New Form of Condensed Hydrogen

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