State-selective charge transfer in slow collisions of with H and

Beijers, Johannes; Hoekstra, Ronnie; Morgenstern, R.

doi:10.1088/0953-4075/29/7/020

Cited by 15 publications

(24 citation statements)

References 31 publications

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“…QMOCC results have confirmed these departures (O 3+ , N 4+ , Stancil et al, 1997) and have predicted it for the B 2+ + H collision system . It was also found in the O 3+ + H QMOCC study that the triplet/singlet ratio for capture to the O 2+ (2p3p) configuration exceeded 3 becoming as large as 10, but these states were not measured by Beijers et al (1996). In Figure 41 we show the triplet/singlet ratios for the O 7+ + He system .…”

Section: The Triplet-singlet Ratiomentioning

confidence: 66%

“…Experimental studies of low charged ions colliding with H have found significant departures of the triplet/singlet ratio from 3 for energies less than ∼ 1 keV/u (O 3+ , Beijers et al, 1996;N 4+ , Bliek et al, 1998) with the ratio steadily decreasing below 3 with decreasing energy. QMOCC results have confirmed these departures (O 3+ , N 4+ , Stancil et al, 1997) and have predicted it for the B 2+ + H collision system .…”

Section: The Triplet-singlet Ratiomentioning

confidence: 99%

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X-ray and extreme ultraviolet emissions from comets

2004

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There is significant progress in the observations, theory, and understanding of the x-ray and EUV emissions from comets since their discovery in 1996. That discovery was so puzzling because comets appear to be more efficient emitters of x-rays than the Moon by a factor of 80 000. The detected emissions are general properties of comets and have been currently detected and analyzed in thirteen comets from five orbiting observatories. The observational studies before 2000 were based on x-ray cameras and low resolution (E/δE ≈ 1.5 -3) instruments and focused on the morphology of xrays, their correlations with gas and dust productions in comets and with the solar x-rays and the solar wind. Even those observations made it possible to choose uniquely charge exchange between the solar wind heavy ions and cometary neutrals as the main excitation process. The recently published spectra are of much better quality and result in the identification of the emissions of the multiply charged ions of O, C, Ne, Mg, and Si which are brought to comets by the solar wind. The observed spectra have been used to study the solar wind composition and its variations. Theoretical analyses of x-ray and EUV photon excitation in comets by charge exchange, scattering of the solar photons by attogram dust particles, energetic electron impact and bremsstrahlung, collisions between cometary and interplanetary dust, and solar x-ray scattering and fluorescence in comets have been made. These analyses confirm charge exchange as the main excitation mechanism, which is responsible for more than 90% of the observed emission, while each of the other processes is limited to a few percent or less. The theory of charge exchange and different methods of calculation for charge exchange are considered. Laboratory studies of charge exchange relevant to the conditions in comets are reviewed. Total and state-selective cross sections of charge exchange measured in the laboratory are tabulated. Simulations of synthetic spectra of charge exchange in comets are discussed. X-ray and EUV emissions from comets are related to different disciplines and fields such as cometary physics, fundamental physics, x-rays spectroscopy, and space physics.

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Section: The Triplet-singlet Ratiomentioning

confidence: 66%

Section: The Triplet-singlet Ratiomentioning

confidence: 99%

X-ray and extreme ultraviolet emissions from comets

2004

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“…Recent works have considered charge transfer in the following collisions: 0 3 + + H (Beijers et al 1996), H+ + C, N, 0 , Si (Kimura et al 1997), C+ + H (Standi et al 1998a), N 2 + + H (Pieksma et al 1997), Si 4+ + H, D , C 5 + + He (Fritsch k Lin 1996), Si 3 + + He (Fang k Kwong 1997;Standi et al 1999), 0 + + O (Hickman et al 1997), and C 2 + + He (McCullough et al 1997). Kingdon k Ferland (1996) have provided analytical fits for low-energy charge transfer between multiply-charged ions and H and made them available on the WWW.…”

Section: Ion-atom and Atom-atom Collisionsmentioning

confidence: 99%

“…Regarding charge transfer for ion-molecule collisions, recent works of interest include the following collisions: N+ + H 2 0 (Dressier et al 1995), 0 3 + + H 2 (Beijers et al 1996), C 2-4+ + H 2 ) C H 4 j C 0 2 ( I t o h e t aL 1 9 9 5^ H + ) D + + H 2 (Ichihara et al 1996), He 2 + , Li 3+ , C 4 +, N 5 + + H 2 (Kumar k Saha 1998), H+ + C 2 H 2 (Kimura et al 1996), C 2 + + H 2 (McCullough et al 1997), H+ + N 2 , 0 2 (Siegmann et al 1998), and 0 + + N 2 (Lindsay et al 1998). …”

Section: Ion-molecule and Atom-molecule Collisionsmentioning

confidence: 99%

Commission 14: Atomic and Molecular Data: (Donnees Atomiques et Moleculaires)

Rostas¹,

Smith²,

Berrington³

et al. 2000

Trans. Int. Astron. Union

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In recognition of its special interdisciplinary character, IAU Commission 14 is linked directly to the Executive Committee. The Commission’s role is to inform the astronomical community of new developments in the diverse fields of research which involve atoms and molecules. Conversely it endeavors to sensitize the research community active in those fields to the specific needs of astronomy, especially concerning basic data and modeling tools. More generally, Commission 14 tries to foster long term relations and collaborations between the two communities and, when necessary, to alert funding authorities to the specific needs of ground and space based astronomy for specific atomic and molecular data. This report is one of the main contributions of Commission 14 to the information of the astronomical community. Several meetings concerned, at least in part, with the need and availability of atomic and molecular data for astrophysics were also sponsored or co-sponsored. In the last triennium, Commission 14 cosponsored IAU Symposium 194 “Astrochemistry: From Molecular Cloud to Planetary Systems” held in Sogwipo (Korea) from Aug. 23 to 27, 1999 and organized by Commission 34. A Joint Discussion: JD1 on “Atomic and Molecular Data for Astrophysics, New Developments, Case Studies and Future Needs” has been planned for the XXIVth IAU General Assembly in Manchester (Aug. 7-19, 2000) and cosponsored by Commissions 15, 16, 29, 34, 36, 40 and 44. Several other Joint Discussions to be held at the Manchester General Assembly are co-sponsored by this commission.

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“…However, the experimental measurements are confined mainly to inert and hydrogen gases [5][6][7][8][9][10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%