Predissociation of H3 <i>n</i>=2 Rydberg states: Product branching and isotope effects

Peterson, J. R.; Devynck, P.; Hertzler, Ch.; Graham, W. G.

doi:10.1063/1.462315

Cited by 26 publications

(7 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Mitchell et al [30] measured the three-body (H + H + H)/two-body(H 2 + H) ratio for DR with vibrationally excited H3 + ions. More recently Peterson et al [31] have measured the same ratio for near-resonant electron capture by 3-keV H3 + in Cs vapor. The three-body/two-body ratio increases with increasing internal ion energy [31].…”

Section: Nismmentioning

confidence: 84%

See 1 more Smart Citation

Direct high-energy neutral-channel dissociative recombination of coldH3+in an ion storage ring

et al. 1993

View full text Add to dashboard Cite

5) IThe cross section for neutral-channel dissociative recombination of vibrationally cooled H3 at energies between 0.0025 and 30 eV has been measured by utilizing the electron cooler at the storage ring CRYRING. The molecular ions were stored at an energy of 32.6 MeV and phase-space cooled by the electron cooler for about 8 s prior to data taking. A peak in the cross section at 9.5 eV is interpreted as a direct adiabatic neutral-channel recombination through the 2 A1 resonant state. The cross section below 1 eV is in rather good agreement with single-pass data.PACS numbers: 34.80.Kw Few cross sections in molecular physics have received such attention as that for the process of dissociative recombination (DR) of H3"*" (cf. Ref. 1). The reason for this is twofold. First, H3 + is the most important molecular ion for the chemistry in interstellar clouds, where it is formed from reactions between neutral and ionized hydrogen and can readily protonize oxygen, carbon, and other heavy atoms. This is the beginning of the formation of nearly one hundred different molecules. The dominant loss process of H3"*" in this environment is dissociative recombination with low-energy electrons. H3 + has also been observed in other astrophysical objects such as the Jovian atmosphere [2] and supernova 1987A [3], The H3 + abundance in these sources depends critically on the DR cross section. Second, there is a 4 orders of magnitude spread between different laboratory measurements of the DR destruction rate [4][5][6][7][8][9][10][11][12][13][14][15]. Theoretical calculations favor a small recombination rate [16,17]. Figure 1 shows potential curves of H3 + and H3 relevant for the process of dissociative recombination.The merged-beam technique used by Mitchell and coworkers [1,6,7,12] offers the cleanest conditions so far for studying collisions between electrons and H3 4 " at welldefined, low center-of-mass energies (0.01-1.0 eV). There is clear experimental and theoretical evidence that the DR cross section of H3 + depends critically on the initial vibrational state distribution [1,12,17,18]. In the most recent merged-beam work the ions were therefore produced in an ion-trap source with a residence time of several milliseconds before extraction [12,18]. Calculations of Einstein A coefficients of low vibrational levels of H 3 + show that lifetimes in the range 100-1000 ms are expected for some levels [19]. It would therefore seem that a confinement time of milliseconds [12] may be insufficient to guarantee a complete vibrational relaxation; however, provided that the source pressure is sufficient, collisional deexcitation is the dominant mecha- nism.Heavy-ion storage rings have been used extensively during recent years for atomic physics experiments. The applicability of these facilities for studies of DR of molecular ions was recently pointed out [20] and investigated quantitatively in a case study [21]. It was shown that the main advantages with the storage ring technique for DR measurements are control over internal modes of excitatio...

show abstract

Section: Nismmentioning

confidence: 84%

“…More recently Peterson et al [31] have measured the same ratio for near-resonant electron capture by 3-keV H3 + in Cs vapor. The three-body/two-body ratio increases with increasing internal ion energy [31]. DR branching-ratio experiments with relatively cool H3 4 " (r=0,1) indicate that the channel \\$ + +e-* H3* play an important role [32].…”

Section: Nismmentioning

confidence: 84%

Direct high-energy neutral-channel dissociative recombination of coldH3+in an ion storage ring

et al. 1993

View full text Add to dashboard Cite

show abstract

“…Predissociation of H 3 Rydberg states has attracted much interest over the past two decades [1][2][3][4][5][6][7][8][9][10][11][12]. There are two major reasons for the persistent attention to this subject.…”

Section: Introductionmentioning

confidence: 99%

Formation of fragment momentum correlations in three-body predissociation of triatomic hydrogen: The interplay of geometry-dependent nonadiabatic coupling and ground-state dynamics

Galster

2010

Phys. Rev. A

View full text Add to dashboard Cite

Momentum correlations in three-body predissociation of triatomic hydrogen are investigated by quasiclassical trajectory calculations. It is shown that nonadiabatic couplings that trigger predissociation of the 2sA 1 state of H 3 imprint their geometric properties on the momentum correlation structures observed after dissociation. A simple symmetry-based model of the geometric coupling properties succeeds in reproducing most of the experimentally observed patterns. The ground-state dynamics that transform the geometric properties of the coupling into the final momentum correlations are identified.

show abstract

“…For larger molecules, three-body decay may constitute a major fragmentation pathway and has come into the focus of recent investigations [11][12][13][14]. In the case of H 3 , Peterson et al [15] found evidence for this process in dissociative charge transfer of H 1 3 in Cs, and Datz et al [16] measured the branching between two-body and three-body channels in dissociative recombination of H 1 3 with electrons. Three-body decay of laser-prepared Rydberg states of H 3 was discovered by translational spectroscopy where two fragments were detected in coincidence [17].…”

mentioning

confidence: 98%

Fragment Correlation in the Three-Body Breakup of Triatomic Hydrogen

et al. 1999

View full text Add to dashboard Cite

We investigate the fragmentation of the triatomic hydrogen molecule H 3 in a triple-coincidence experiment. A single rovibronic state of H 3 is laser prepared and its breakup into three hydrogen atoms H͑1s͒ is monitored by time-and position-sensitive multihit detectors. For each triple hit, the momentum vectors of the three H͑1s͒ fragments are determined. The sixfold differential cross section of the fragment momentum components in the center-of-mass frame is found to be highly structured and to depend sensitively on the H 3 initial electronic state.

show abstract

Predissociation of H3 n=2 Rydberg states: Product branching and isotope effects

Cited by 26 publications

References 24 publications

Direct high-energy neutral-channel dissociative recombination of coldH3+in an ion storage ring

Direct high-energy neutral-channel dissociative recombination of coldH3+in an ion storage ring

Formation of fragment momentum correlations in three-body predissociation of triatomic hydrogen: The interplay of geometry-dependent nonadiabatic coupling and ground-state dynamics

Fragment Correlation in the Three-Body Breakup of Triatomic Hydrogen

Contact Info

Product

Resources

About