Role of excited electronic states in the interactions of fast (MeV) molecular ions with solids and gases

Kanter, E. P.; Cooney, Patrick J.; Gemmell, D. S.; Groeneveld, K. O.; Pietsch, W.; Ratkowski, Anthony J.; Vager, Z.; Zabransky, B. J.

doi:10.1103/physreva.20.834

Cited by 117 publications

(17 citation statements)

References 32 publications

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“…[14] and Zajfman et al [15]. It has been shown that a Boltzmann distribution is obtained with an effective temperature T, rr which depends on the type of the ion source and its operating parameters.…”

Section: Iu Results and Discussionmentioning

confidence: 99%

Mean lifetime of the bound 2pσ state ofHeH2+

et al. 1994

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Recently, experimental evidence for the existence of a bound state of the HeH + molecular ion was reported by Ben-ltzhak, Gertner, Heber, and Rosner [Phys. Rev. Lett. 71 1347 (1993)]. This three-bod system was predicted by Bates and Carson to have bound vibrational states in the 2pcr electronic state despite the strong repulsion potential between the two nuclei. These 2po. vibrational states decay via an e ectronic transition to the 1so. repulsive ground state with a mean lifetime of about 1 nsec. We have 1 u ed the "fragment-fragment" coincidence method to measure the mean lifetime of the HeH'+ molecular ions which dissociate in Aight before reaching the detector. The yield of these molecular ions was measured as a function of the distance between the target cell and the analyzer exit. From this measurement a mean lifetime of 3.9+0.4 nsec was determined. The 2po.~iso. transition rates for all vibrational states have been calculated within the Born-Oppenheimer approximation using available oscillator strengths. It is shown that the transition rates decrease with increasing vibrational energy because of the " tretch" of the molecular ion. The distribution of 2po. vibrational states populated by vertical transitions from stripping the HeH+ electronic ground state was evaluated, and the resulting decay curve compares well with the measured one.PACS number(s): 34.50.Gb, 35.80.+s

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Section: Iu Results and Discussionmentioning

confidence: 99%

Mean lifetime of the bound 2pσ state ofHeH2+

et al. 1994

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“…(4) and (5) have been fulfilled in many studies of Coulomb explosion and have been pushed to the limits by the high resolution experiments reported in Ref. 2. With respect to ion surface scattering the situation is clearly different.…”

Section: Radiation Effects and Defects In Solidsmentioning

confidence: 90%

Dissociation of Fast H⁺₂-molecular ions in grazing surface collisions

Winter

1991

Radiation Effects and Defects in Solids

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The dissociation of H: -molecules with energies ranging from 0.4 to 1.6 MeV in grazing collisions with a clean and atomically flat W(100)-surface is investigated by spectroscopy of the energy of the dissociated fragments. We observe two peaks in the energy spectra which result from the Coulomb explosion in longitudinal direction during surface scattering. Intensities and widths of both peaks are clearly different and depend strongly on the angle of scattering.

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“…Though it is known that molecular ions from accelerator ion sources can be in highly excited vibrational states -e.g. the most probable internuclear distance is changed from 2.0 to 2.2 [10] -the experimental accuracy is too low at the moment to see effects of this kind in electron loss data [11,12]. In conclusion the analysis has shown that inelastic atom-electron scattering is a promising tool to investigate Compton profiles of molecular ions.…”

Section: (Dcr)mentioning

confidence: 86%

Molecular compton profiles from inelastic atom-electron scattering

Bell

1984

Z Physik A

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Recent measurements of the electron loss peak from H~-ions impinging on Ar have been analyzed in terms of projectile Compton profiles (CP). It is shown that projected momentum distributions, i.e. CP's, can be determined for the molecular ion H~-.Recently it has been demonstrated that Compton profiles (CP), i.e. projected electron momentum distributions, of either target atoms or projectile ions can be obtained by inelastic ion-electron scattering [1]. It is the aim of this paper to show that existing data of electron loss measurements are sensitive enough to extract the Compton profile of H~-molecules. (For a recent review of molecular Compton profiles see [2].) We have analyzed the electron loss peak (ELP) measurements of K6v6r et al. [3] for H~--Ar and He +-Ar collisions in terms of CP's. If the collision velocity v is much larger than the initial orbital velocity v~ of the scattered electrons, the double differential cross section (DDCS) for the emission of projectile electrons can be factorized [1] :Here, (da/df2)e is the elastic cross section for scattering an electron with velocity v at a screened target nucleus and Jp(p=) the CP of the projectile:O~(p) is the initial electron wave-function, E e the electron lab energy and Eem the electron energy at which the electron loss peak occurs (atomic units are used). The essential feature of (1) is that the DDCS factorizes into a cross section which contains all the information of the electron-atom interaction and which is essentially constant in the region of the ELP and a CP which is characteristic of the electron's initial state. For the evaluation of (1) where N is a normalization constant. Putting (4) into (2) yields a directional CP which has to be averaged over all angles between the momentum component p~ (which is parallel to the beam direction) and the bond direction /~ assuming an isotropic distribution of/~ with respect to $ [7]. Figure 1 shows the comparison of experimental data of [3] for 0.8 MeV/amu He + (circles), 0.8 MeV/ amu H~-(closed triangles) and 1.995 MeV/

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Role of excited electronic states in the interactions of fast (MeV) molecular ions with solids and gases

Cited by 117 publications

References 32 publications

Mean lifetime of the bound 2pσ state ofHeH2+

Mean lifetime of the bound 2pσ state ofHeH2+

Dissociation of Fast H⁺₂-molecular ions in grazing surface collisions

Molecular compton profiles from inelastic atom-electron scattering

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Role of excited electronic states in the interactions of fast (MeV) molecular ions with solids and gases

Cited by 117 publications

References 32 publications

Mean lifetime of the bound 2pσ state ofHeH2+

Mean lifetime of the bound 2pσ state ofHeH2+

Dissociation of Fast H+2-molecular ions in grazing surface collisions

Molecular compton profiles from inelastic atom-electron scattering

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Dissociation of Fast H⁺₂-molecular ions in grazing surface collisions