Translational energy spectroscopy of single-electron capture by C2+ ions in He, Ne and Ar

Lee, A.R.; Wilkins, Adam C. R.; Enos, C.S.; Brenton, A.G.

doi:10.1016/0168-1176(94)03998-4

Cited by 12 publications

(7 citation statements)

References 12 publications

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“…C + (1s 2 2s 2 2p) 2 P formation (peak M1) involves core conservation and the minor channel (peak M3) involving a core rearrangement process accounts for very little of the total C + yield. The previous TES measurements of oneelectron capture in C 2+ -Ne collisions by Lennon et al (1983) in this laboratory and by Lee et al (1994) using C 2+ beams with unknown metastable content are in good qualitative agreement with the present work. For Ne, the total one-electron capture cross section ratio σ ( 3 P)/σ ( 1 S) derived from the plots in figure 3(b) is 3.1 ± 0.2.…”

Section: One-electron Capture In Collisions Of Ground-state and Metas...supporting

confidence: 92%

“…The minor peak M2 The present DTES measurements provide more detailed information on the one-electron capture process than previous TES measurements on the C 2+ -He system carried out with primary beams of unknown metastable content. If the C 2+ + He data of Lee et al (1994) are considered, even with their good energy resolution of 0.3 eV FWHM, their unspecified beam composition leads to confusion in their peak assignments. For example, they suggested that an observed peak at 2.8 eV in their energy change spectrum might be associated with the presence of primary-beam ions in a second 'metastable' C 2+ (2p 2 ) 3 P state although, according to Wiese et al (1966), this state has a lifetime of only 7.7 × 10 −10 s. In fact, the present energy change spectrum (figure 3(b)) for one-electron capture by a pure groundstate C 2+ beam in collisions with He, a process for which there are no exothermic product channels, shows that their unexplained peak at 2.8 eV can be identified with the background contaminant product channel G2.…”

Section: One-electron Capture In Collisions Of Ground-state and Metas...mentioning

confidence: 99%

“…Although C 2+ + Ar has been extensively studied at various impact energies by Lennon et al (1983), Unterreiter et al (1991), Lee et al (1994Lee et al ( , 1995, the present use of DTES to separate the product channels corresponding to either ground or metastable primary ions provides more detailed information. In figure 6(a) our observed energy change spectrum for a 4 keV beam of C 2+ ions of unknown metastable content may be compared with the corresponding spectra (figures 6(b) and (c)) for pure ground-state C 2+ ( 1 S) and pure C 2+ ( 3 P) metastable ions prepared by TES.…”

Section: One-electron Capture In Collisions Of Ground-state and Metas...mentioning

confidence: 99%

“…Our cross section ratio σ ( 3 P)/σ ( 1 S) may also be used to estimate the metastable fractions present in the 4 keV measurements of Unterreiter et al (1991) and Lee et al (1994). Although Unterreiter et al (1991) used an attenuation technique to estimate a fraction f = 0.10±0.01, our analysis of the two largest peaks in their energy change spectrum together with our measured ratio σ (M2)/σ (G3) indicates the rather larger fraction of f = 0.17 ± 0.02.…”

Section: One-electron Capture In Collisions Of Ground-state and Metas...mentioning

confidence: 99%

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State-selective one-electron capture from He, Ne and Ar by 4 keV state-prepared ions

Greenwood¹,

Burns²,

McCullough³

et al. 1996

J. Phys. B: At. Mol. Opt. Phys.

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A new instrument to carry out double-translational energy spectroscopy (DTES) recently developed in this laboratory has been described in detail. This permits studies of state-selective electron capture by slow state-prepared multiply charged ions using translational energy spectroscopy (TES). The effectiveness and future potential of this approach has been illustrated by studies of one-electron capture in helium, neon and argon by 4 keV beams of pure ground-state and pure metastable ions. In each case the main product channels have been identified by TES and analysed quantitatively without the ambiguities associated with previous measurements which used primary ion beams containing a mixture of ground and metastable species. A simple beam attenuation technique has also been used in conjunction with our state-prepared beams to provide estimates of the ratios of the total one-electron capture cross sections which, in each case, show that is considerably larger than . These ratios have in turn been used to show that the metastable content of ions from the present ECR ion source and sources used in other laboratories can be substantial.

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Section: One-electron Capture In Collisions Of Ground-state and Metas...supporting

confidence: 92%

Section: One-electron Capture In Collisions Of Ground-state and Metas...mentioning

confidence: 99%

Section: One-electron Capture In Collisions Of Ground-state and Metas...mentioning

confidence: 99%

Section: One-electron Capture In Collisions Of Ground-state and Metas...mentioning

confidence: 99%

See 2 more Smart Citations

State-selective one-electron capture from He, Ne and Ar by 4 keV state-prepared ions

Greenwood¹,

Burns²,

McCullough³

et al. 1996

J. Phys. B: At. Mol. Opt. Phys.

View full text Add to dashboard Cite

show abstract

“…The first TES study of one-electron capture by C 2+ ions in Ar was carried out in this laboratory (Lennon et al 1983) in the energy range 1-6 keV. There have been several other TES studies (Unterreiter et al 1991, Lee et al 1994 for C 2+ energies in the range 0.5-8 keV. All of these spectra, which are in good qualitative agreement with one another, contain a number of peaks which could be unambiguously attributed to either C 2+ (2s 2 ) 1 S ground-state ions or C 2+ (2s2p) 3 P metastable ions.…”

Section: Letter To the Editor L601mentioning

confidence: 99%

The first use of state-prepared beams of in studies of state-selective electron capture collisions

Greenwood

Burns

McCullough

et al. 1996

J. Phys. B: At. Mol. Opt. Phys.

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The use of double translational energy spectroscopy has been successfully demonstrated to allow studies of state-selective electron capture with state-prepared primary ions. Excited product channels arising from one-electron capture by 4 keV C 2+ ( 1 S) groundstate and C 2+ ( 3 P) metastable ions in collisions with argon have been separately identified.Electron capture by multi-charged ions at impact energies less than 25 keV amu −1 of the type X q+ + Y → X (q−1)+ (n, l) + Y +

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Translational energy spectroscopy. Spin‐conservation studies in collisional excitation processes

Enos

Lee

Brenton

1995

Rapid Comm Mass Spectrometry

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High-resolution translational energy spectroscopy is an effective means of obtaining detailed state-selective information, permitting systematic investigation of spin conservation in collisional processes. In this paper, we examine collisional excitation of one selected singlet (N3 and one non-singlet ( 0 3 target by a variety of projectile ions, providing a kaleidoscope of assorted effects.The concept of spin conservation in collisional processes first appeared in an article on quantum mechanics written by Eugene Wigner during his Goettingen period,' and has been the subject of numerous studies ever since. Early experimental support for spin conservation came from the work of Beutler and Eisenschimme12 who monitored the triplet and singlet radiations emitted by excited mercury atoms in a gaseous discharge. They found that addition of metastable krypton ('P) to the discharge enhanced the triplet radiation without substantially affecting the intensity of the singlet radiation. This can be understood in terms of the multiplicities of the participating atoms in the two processes:The first of these is in accord with the spin-conservation requirement and therefore leads to enhancement of the triplet radiation, whereas the second process violates spin conservation and is accordingly suppressed. Contemporary investigations by M~o r e~.~ for inelastic collisions of N+ ions with inert gas atoms and diatomic molecules (N, and 0,) revealed that spin conservation was generally observed for all excitation and deexcitation processes, except for some weak spin violation attributed to strong spin-orbit coupling in the relevant ion-atom/ion-molecule systems. However, one of their reported spin non-conserved processes, involving the simultaneous atomic N+('D+ IS) and molecular 0,(X3X;+ G 'Ag) transitions in N+-02, was not detected in our recent high-resolution studies of this collision ~y s t e m .~ In single electron capture, studies by Sat0 and Moore6 on capture by N2+ in He and Ne also confirmed spin conservation in all observed channels. This is in accord with our own recent investigation of single electron capture (SEC) by N2+ ions, as well as SEC by C2+, C3+ and 02+ from He, Ne and Ar By contrast, double electron capture (DEC) processes are often associated with spin violation. This is exemplified by the observation of Fourier et a[." in DEC collisions of H' with Xe atoms in translationalenergy studies. Our own studies involving double electron capture by Xe3+ and Kr3+ in Ar and KrI2 and Ar4+ states is strictly forbidden with the 2H+ and He2+ product target ions being permanent singlets. They found that the results for collisions of He2+ with H2 were in accord with the spin rule, but significant triplet emissions following He2+/He collisions indicated a spin violation and were attributed to the dominations of short range effects. Our current observations", l3 appear to support this view.The Wigner spin-conservation rule', 4, l9 requires that the total spin angular momentum should remain unchanged in the course of a collision...

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Translational energy spectroscopy of single-electron capture by C2+ ions in He, Ne and Ar

Cited by 12 publications

References 12 publications

State-selective one-electron capture from He, Ne and Ar by 4 keV state-prepared ions

State-selective one-electron capture from He, Ne and Ar by 4 keV state-prepared ions

The first use of state-prepared beams of in studies of state-selective electron capture collisions

Translational energy spectroscopy. Spin‐conservation studies in collisional excitation processes

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