Progress in stored ion beam experiments on atomic and molecular processes

Wolf, A.; Buhr, H.; Grieser, M.; Hahn, R. von; Lestinsky, M.; Orlov, D. A.; Lindroth, Eva; Schneider, I. F.; Schippers, S.

doi:10.1007/978-3-540-73466-6_15

Cited by 3 publications

(4 citation statements)

References 37 publications

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“…For the present experiment 197 Au 20+ ions were produced by the MPIK linear accelerator facility and injected into TSR with an energy of 180 MeV. In two of the straight sections of the storage ring, electron beams were guided by magnetic fields such that they moved collinearly (centered on the same axis) with the ion beam [7]. One of the electron beams was used for continuous electron cooling of the ion beam and the other was used as an electron target for the recombination measurements.…”

Section: Methodsmentioning

confidence: 99%

Recombination of Au²⁰⁺at low electron–ion collision energies

et al. 2011

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Section: Methodsmentioning

confidence: 99%

Recombination of Au²⁰⁺at low electron–ion collision energies

et al. 2011

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“…In the recombination of electrons with hydrogen molecular ions, rovibrational resonances have been measured down to a few meV. 18 Electrons with translational temperatures of a few K have been created using a cryogenic photocathode. To cool the ions, e.g.…”

Section: Guided Ion Beam Merged With a Neutral Beammentioning

confidence: 99%

“…18. Phase space calculation of state specific cross sections for the reaction N( 3 P 0 ) + + H 2 (j) → NH + + H. The endothermicity which is not yet known with the required accuracy, has been assumed to be ∆H = 17.5 meV and 15 meV.…”

mentioning

confidence: 99%

The Study of Cold Collisions Using Ion Guides and Traps

Gerlich¹

2008

Low Temperatures and Cold Molecules

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“…The response of the DR rate coefficients to T exc have been investigated only for light ions (e.g., Amitay et al 1996a, Zhaunerchyk et al 2007, Petrignani et al 2011, Schwalm et al 2011. From these few studies we are unable to draw predictions for NH + DR data with T exc < 300 K. Future studies at MPIK using the currently under construction Cryogenic Storage Ring, which will have an internal ambient temperature of ∼ 10 K, will be able to address this issue (Fadil et al 2006;Wolf et al 2006;Krantz et al 2011;von Hahn et al 2011).…”

Section: Astrochemical Implicationsmentioning

confidence: 99%

DISSOCIATIVE RECOMBINATION MEASUREMENTS OF NH⁺USING AN ION STORAGE RING

Novotný

Berg

Bing

et al. 2014

ApJ

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We have investigated dissociative recombination (DR) of NH + with electrons using a merged beams configuration at the TSR heavy-ion storage ring located at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. We present our measured absolute merged beams recombination rate coefficient for collision energies from 0 to 12 eV. From these data we have extracted a cross section which we have transformed to a plasma rate coefficient for the collisional plasma temperature range from T pl = 10 to 18000 K. We show that the NH + DR rate coefficient data in current astrochemical models are underestimated by up to a factor of ∼ 9. Our new data will result in predicted NH + abundances lower than calculated by present models. This is in agreement with the sensitivity limits of all observations attempting to detect NH + in interstellar clouds.In the cold ISM, such as in molecular clouds, the most abundant nitrogen-bearing species are expected to be N and N 2 (Langer & Graedel 1989). However, direct observation of these is difficult. Atomic N does not have any low-lying, fine-structure levels that can be populated at molecular cloud temperatures and N 2 lacks a dipole moment, which is needed to provide reasonably strong ro-vibrational transitions. Thus, observations of tracers such as NH, NH 2 , NH 3 , or N 2 H + must be used to infer the N and N 2 abundances through chemical models.Neutral nitrogen hydrides are widely seen in the ISM. Ammonia (NH 3 ) was first detected by Cheung et al. (1968). Later NH 2 and NH were identified by van Dishoeck et al. (1993) and Meyer & Roth (1991), respectively. The observed abundances, however, do not match predictions from astrochemical models. In diffuse interstellar clouds, observed abundance ratio for NH/NH 3 are ∼ 1.7 and for NH 3 /H ∼ 3.2 × 10 −9 . These cannot be simultaneously explained by existing chemical models. The models can fit either one of the observed values but then the other predicted ratio is a factor of 10 off from the observation (Persson et al. 2010). Similarly, in dark clouds the abundance ratio for NH/NH 3 is underpredicted by more than an order of magnitude (Hily-Blant et al. 2010). These discrepancies possibly originate from using incorrect reaction rate coefficients in the models.

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Progress in stored ion beam experiments on atomic and molecular processes

Cited by 3 publications

References 37 publications

Recombination of Au²⁰⁺at low electron–ion collision energies

Recombination of Au²⁰⁺at low electron–ion collision energies

The Study of Cold Collisions Using Ion Guides and Traps

DISSOCIATIVE RECOMBINATION MEASUREMENTS OF NH⁺USING AN ION STORAGE RING

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Progress in stored ion beam experiments on atomic and molecular processes

Cited by 3 publications

References 37 publications

Recombination of Au20+at low electron–ion collision energies

Recombination of Au20+at low electron–ion collision energies

The Study of Cold Collisions Using Ion Guides and Traps

DISSOCIATIVE RECOMBINATION MEASUREMENTS OF NH+USING AN ION STORAGE RING

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Recombination of Au²⁰⁺at low electron–ion collision energies

Recombination of Au²⁰⁺at low electron–ion collision energies

DISSOCIATIVE RECOMBINATION MEASUREMENTS OF NH⁺USING AN ION STORAGE RING