Observation of a Rydberg Series in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi mathvariant="normal">H</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi mathvariant="normal">H</mml:mi><mml:mo>−</mml:mo></mml:msup></mml:math>: A Heavy Bohr Atom

Vieitez, M.O.; Ivanov, T.I.; Reinhold, E.M.; Lange, C.A. de; Ubachs, Wim

doi:10.1103/physrevlett.101.163001

Cited by 37 publications

(44 citation statements)

References 23 publications

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“…These studies found the spectra dominated by relatively short-range electronic molecular states. It was only recently that Vieitez et al observed spectral features corresponding to bound ion-pair states by using a laser-based xuv light source in a two-photon excitation scheme [19,20]. Consistent with the earlier investigations, the ion-pair resonances were observed in the photoexcitation yield of H coupling with short-range electronic molecular states.…”

supporting

confidence: 72%

Spectroscopic observation of bound ungerade ion-pair states in molecular hydrogen

Ekey

McCormack

2011

Phys. Rev. A

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supporting

confidence: 72%

Spectroscopic observation of bound ungerade ion-pair states in molecular hydrogen

Ekey

McCormack

2011

Phys. Rev. A

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“…Selection rules impose that only Rydberg states converging to V + ) 6, N + ) 1 and 3 should be observable, which is indeed the case. Again, qualitatively some features of series interaction are visible in the spectrum of Figure 3 in ref 23. In the Rydberg series converging to V + ) 6, N + ) 3 the Fano q-parameter is found to vary as a function of the principal quantum number, indicative of an interaction between multiple channels.…”

Section: Experiments and Observationsmentioning

confidence: 76%

Spectroscopic Observation and Characterization of H⁺H⁻ Heavy Rydberg States

et al. 2009

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A series of discrete resonances was observed in the spectrum of H 2 , which can be unambiguously assigned to bound quantum states in the 1/R Coulombic potential of the H + H -ion-pair system. Two-step laser excitation was performed, using tunable extreme ultraviolet radiation at λ ) 94-96 nm in the first step, and tunable ultraviolet radiation in the range λ ) 310-350 nm in the second step. The resonances, detected via H + and H 2 + ions produced in the decay process, follow a sequence of principal quantum numbers (n ) 140-230) associated with a Rydberg formula in which the Rydberg constant is mass scaled. The series converges upon the ionic H + H -dissociation threshold. This limit can be calculated without further assumptions from known ionization and dissociation energies in the hydrogen system and the electronegativity of the hydrogen atom. A possible excitation mechanism is discussed in terms of a complex resonance. Detailed measurements are performed to unravel and quantify the decay of the heavy Rydberg states into molecular H 2 + ions, as well as into atomic fragments, both H(n ) 2) and H(n ) 3). Lifetimes are found to scale as n 3 .

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“…The states that undergo polar dissociation, though repulsive in the Franck-Condon region, will have minima at large internuclear separations, due to the 1=r potential between the fragments. These states have been shown to behave like a heavy Bohr atom with H À ion being orbited by a proton with large principal quantum numbers [27,28]. Several states that undergo vibrational autoionization and polar dissociation by photoabsorption in the range of 17.37-17.62 eV have been identified in H 2 , HD, and D 2 [29].…”

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confidence: 99%

Dissociative Electron Attachment Cross Sections forH2andD2

et al. 2011

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New measurements of the absolute cross sections for dissociative electron attachment (DEA) in molecular hydrogen and deuterium are presented which resolve previous ambiguities and provide a test bed for theory. The experimental methodology is based upon a momentum imaging time-of-flight spectrometer that allowed us to eliminate any contributions due to electronically excited metastable neutrals and ultraviolet light while ensuring detection of all the ions. The isotope effect in the DEA process in the two molecules is found to be considerably larger than previously observed. More importantly, it is found to manifest in the polar dissociation process (also known as ion pair production) as well. DOI: 10.1103/PhysRevLett.106.243201 PACS numbers: 34.80.Ht Dissociative electron attachment (DEA) in hydrogen is of fundamental importance as one of the benchmark cases in atomic collisions. Together with its reverse process of associative detachment (AD), it is also relevant to the studies in astrophysics [1-3], development of ion sources [4], and in fusion edge plasmas [5,6]. Three distinct resonant processes leading to negative ion production (H À and/ or D À ) were studied and absolute cross sections (CSs)À , and its isotopologues HD and D 2 have been reported. These three processes are believed to proceed through the lowest attractive X 2 AE þ u state (4 eV process), the repulsive B 2 AE þ g state (7-13 eV process), and the attractive Rydberg excited state, 2AE þ g (14 eV process) leading to excited H (D). The peak cross section for the most abundant process at 14 eV in H 2 DEA was determined in two independent measurements to be 3:5 Â 10 À20 cm 2 [7] and 2:1 Â 10 À20 cm 2 [8]. These two CS values were the only ones available until now and therefore have been widely quoted and used in many applications. More recently, the CS for the 14 eV process was used to normalize the CS for the 4 eV process in relative CS studies [9,10]. It should be noted that the unusually small number of DEA CS measurements in hydrogen and the still high uncertainty in the CS is mainly due to its very low value. For example, the peak CS for H 2 DEA is 2 orders of magnitude smaller as compared to O 2 DEA. Another important characteristic of DEA in hydrogen is a strong decrease in the CS for heavier isotopologues, HD and D 2 [8,9], due to the strongly reduced survival probability of the dissociative channel.Additional data on DEA in hydrogen have been provided by other experiments: H À angular distributions [11], the strong dependence of DEA at 4 eV on rovibrational excitation [12], and the appearance of interference structures in the CS between 8-12 eV [11] and at 14 eV [13].Two more studies on the relative DEA cross section have been performed with emphasis on the vibrational excitation dependency of the 14 eV resonance in H 2 and D 2 [14] and on the electron energy resolution dependency of the experimental CS for the 4 eV process in H 2 [10]. Because of the increase of the DEA CS by orders of magnitude with vibrational excitation of the t...

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Observation of a Rydberg Series inH+H−: A Heavy Bohr Atom

Cited by 37 publications

References 23 publications

Spectroscopic observation of bound ungerade ion-pair states in molecular hydrogen

Spectroscopic observation of bound ungerade ion-pair states in molecular hydrogen

Spectroscopic Observation and Characterization of H⁺H⁻ Heavy Rydberg States

Dissociative Electron Attachment Cross Sections forH2andD2

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Observation of a Rydberg Series inH+H−: A Heavy Bohr Atom

Cited by 37 publications

References 23 publications

Spectroscopic observation of bound ungerade ion-pair states in molecular hydrogen

Spectroscopic observation of bound ungerade ion-pair states in molecular hydrogen

Spectroscopic Observation and Characterization of H+H− Heavy Rydberg States

Dissociative Electron Attachment Cross Sections forH2andD2

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Spectroscopic Observation and Characterization of H⁺H⁻ Heavy Rydberg States