Dissociative recombination of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">CH</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>: Cross section and final states

Amitay, Zohar; Zajfman, D.; Forck, P.; Hechtfischer, Ulrich; Seidel, B.; Grieser, M.; Habs, D.; Repnow, R.; Schwalm, D.; Wolf, A.

doi:10.1103/physreva.54.4032

Cited by 121 publications

(154 citation statements)

References 41 publications

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“…3. The basic experimental procedures have been described in detail earlier regarding merged electron and ion beam experiments in general [32], DR of molecular ions [33,34], and Coulomb explosion imaging [35,36].…”

Section: A Ion Beam and Detector Setupmentioning

confidence: 99%

“…The average pressure in the storage ring was 5-10 × 10 −11 mbar during the present measurements. The TSR electron cooler [40,41] was used to apply phase space cooling to the stored He + 2 ion beam [42] and to perform the electron-ion recombination experiments [32,33]. The electron beam is guided by a longitudinal magnetic field (∼0.04 T) and has a diameter of 29.5 mm in the region where the electron and ion beam overlap collinearly, surrounded by a 1.5 m long solenoid magnet.…”

Section: A Ion Beam and Detector Setupmentioning

confidence: 99%

“…Instead of the surface barrier detector, also a multiparticle imaging detector [33] could be used in the detector chamber. From an 80-mm diameter multichannel plate, equipped with a phosphor screen, the transverse coordinates of all fragments arriving within a coincidence time window of a few microseconds, is read out with an event-triggered camera system.…”

Section: A Ion Beam and Detector Setupmentioning

confidence: 99%

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Dissociative recombination and low-energy inelastic electron collisions of the helium dimer ion

et al. 2005

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The dissociative recombination (DR) of 3 He 4 He + has been investigated at the heavy-ion Test Storage Ring (TSR) in Heidelberg by observing neutral products from electron-ion collisions in a merged beams configuration at relative energies from near-zero (thermal electron energy about 10 meV) up to 40 eV. After storage and electron cooling for 35 s, an effective DR rate coefficient at nearzero energy of 3 × 10 −9 cm 3 s −1 is found. The temporal evolution of the neutral product rates and fragment imaging spectra reveals that the populations of vibrational levels in the stored ion beam are non-thermal with fractions of ∼0.1-1% in excited levels up to at least v = 4, having a significant effect on the observed DR signals. With a pump-probe-type technique using DR fragment imaging while switching the properties of the electron beam, the vibrational excitation of the ions is found to originate mostly from ion collisions with the residual gas. Also, the temporal evolution of the DR signals suggests that a strong electron induced rotational cooling occurs in the vibrational ground state, reaching a rotational temperature near or below 300 K. From the absolute rate coefficient and the shape of the fragment imaging spectrum observed under stationary conditions, the DR rate coefficient from the vibrational ground state is determined; converted to a thermal electron gas at 300 K it amounts to (3.3 ± 0.9) × 10 −10 cm 3 s −1 . The corresponding branching ratios from v = 0 to the atomic final states are found to be (3.7 ± 1.2)% for 1s2s 3 S, (37.4 ± 4.0)% for 1s2s 1 S, (58.6 ± 5.2)% for 1s2p 3 P , and (2.9 ± 3.0)% for 1s2p 1 P . A DR rate coefficient in the range of 2 × 10 −7 cm 3 s −1 or above is inferred for vibrational levels v = 3 and higher. As a function of the collision energy, the measured DR rate coefficient displays a structure around 0.2 eV. At higher energies, it has one smooth peak around 7.3 eV and a highly structured appearance at 15-40 eV. The small size of the observed effective DR rate coefficient at near-zero energy indicates that the electron induced rotational cooling is due to inelastic electron-ion collisions and not due to selective depletion of rotational levels by DR.

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Section: A Ion Beam and Detector Setupmentioning

confidence: 99%

Section: A Ion Beam and Detector Setupmentioning

confidence: 99%

Section: A Ion Beam and Detector Setupmentioning

confidence: 99%

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Dissociative recombination and low-energy inelastic electron collisions of the helium dimer ion

et al. 2005

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“…The CD + ions arrive at the interaction region with the laser in a combination of the electronic ground state, X 1 + , and the lowest triplet state, namely, the a 3 , which has a lifetime of a few seconds [54]-much longer than the few tens of microseconds flight time through our apparatus. This long-lived triplet state may constitute about half the CD + beam [54,55]. Moreover, the vibrational distribution in both electronic states is possibly vibrationally "hot" [56] and may affect the outcome of the laser interaction with the CD + molecular ions.…”

Section: Experimental Methodsmentioning

confidence: 99%

Fragmentation ofCD+induced by intense ultrashort laser pulses

et al. 2015

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The fragmentation of CD + in intense ultrashort laser pulses was investigated using a coincidence threedimensional momentum imaging technique improved by employing both transverse and longitudinal electric fields. This allowed clear separation of all fragmentation channels and the determination of the kinetic energy release down to nearly zero, for a molecule with significant mass asymmetry. The most probable dissociation pathways for the two lowest dissociation limits, C + + D and C + D + , were identified for both 22-fs, 798-nm and 50-fs, 392-nm pulses. Curiously, the charge asymmetric dissociation of CD 2+ was not observed for 392-nm photons, even though it was clearly visible for the fundamental 798 nm at the same peak intensity.

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“…Mostly, the transverse momenta of all recombination fragments are recorded event by event using a spatially resolving multi-hit detector (two-dimensional fragment imaging) [25]. Space and time-resolving multi-hit detectors also have been used in some cases for three-dimensional fragment imaging.…”

Section: Electron Interactions With Molecular Ionsmentioning

confidence: 99%

Cooling of molecular ion beams

Wolf

Krohn

Kreckel

et al. 2004

Nuclear Instruments and Methods in Physics Research Section A:

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An overview of the use of stored ion beams and phase space cooling (electron cooling) is given for the field of molecular physics. Emphasis is given to interactions between molecular ions and electrons studied in the electron cooler: dissociative recombination and, for internally excited molecular ions, electron-induced ro-vibrational cooling. Diagnostic methods for the transverse ion beam properties and for the internal excitation of the molecular ions are discussed, and results for phase space cooling and internal (vibrational) cooling are presented for hydrogen molecular ions.

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Dissociative recombination ofCH+: Cross section and final states

Cited by 121 publications

References 41 publications

Dissociative recombination and low-energy inelastic electron collisions of the helium dimer ion

Dissociative recombination and low-energy inelastic electron collisions of the helium dimer ion

Fragmentation ofCD+induced by intense ultrashort laser pulses

Cooling of molecular ion beams

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