Storage Ring Measurement of the C<scp>iv</scp>Recombination Rate Coefficient

Schippers, S.; Müller, A.; Gwinner, G.; Linkemann, J.; Saghiri, A. A.; Wolf, A.

doi:10.1086/321512

Cited by 108 publications

(223 citation statements)

References 41 publications

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“…Such differences between calculated rate coefficients and measured spectra are not uncommon (see e.g. Schippers et al 2001) and are here at the limit of the experimental systematic uncertainties. DR resonance positions shown by the vertical bars were calculated using Eq.…”

Section: Merged-beam Rate Coefficientsmentioning

confidence: 71%

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Experimental dielectronic recombination rate coefficients for Na-like S VI and Na-like Ar VIII

Orbán¹,

Altun

Källberg

et al. 2009

A&A

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Aims. Absolute recombination rate coefficients for two astrophysically relevant Na-like ions are presented.Methods. Recombination rate coefficients of S vi and Ar viii are determined from merged-beam type experiments at the CRYRING electron cooler. Calculated rate coefficients are used to account for recombination into states that are field-ionized and therefore not detected in the experiment. Results. Dielectronic recombination rate coefficients were obtained over an energy range covering Δ n = 0 core excitations. For Na-like Ar a measurement was also performed over the Δ n = 1 type of resonances. In the low-energy part of the Ar viii spectrum, enhancements of more than one order of magnitude are observed as compared to the calculated radiative recombination. The plasma recombination rate coefficients of the two Na-like ions are compared with calculated results from the literature. In the 10 3 −10 4 K range, large discrepancies are observed between calculated plasma rate coefficients and our data. At higher temperatures, above 10 5 K, in the case of both ions our data is 30% higher than two calculated plasma rate coefficients, other data from the literature having even lower values. Conclusions. Discrepancies below 10 4 K show that at such temperatures even state-of-the-art calculations yield plasma rate coefficients that have large uncertainties. The main reason for these uncertainties are the contributions from low-energy resonances, which are difficult to calculate accurately.

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Section: Merged-beam Rate Coefficientsmentioning

confidence: 71%

“…The validity of the above double-convolution for the preparation of plasma recombination rate coefficients was investigated by Schippers et al (2001). Plasma DR rate coefficients obtained from the experimentally derived DR spectrum of Ar viii are shown in Fig.…”

Section: Plasma Dr Rate Coefficientsmentioning

confidence: 99%

Experimental dielectronic recombination rate coefficients for Na-like S VI and Na-like Ar VIII

Orbán¹,

Altun

Källberg

et al. 2009

A&A

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“…2. The above approach of convolution is valid as long as the electron temperatures in the experiment is much lower than the temperature of the Maxwell-Boltzmann energy distribution in plasma (Schippers et al 2001). …”

Section: Plasma Rate Coefficientsmentioning

confidence: 99%

“…To derive field-ionization-free plasma rate coefficients, we used the same procedure as described in Schippers et al (2001) and Fogle et al (2005). The field-effected part of the experimental spectrum was estimated using the calculated results for Rydberg states with n up to 1000 as discussed in the previous section.…”

Section: Plasma Rate Coefficientsmentioning

confidence: 99%

Experimental rate coefficients of F⁵⁺recombining into F⁴⁺

Ali

Orbán

Mahmood

et al. 2013

A&A

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Recombination spectra of F 5+ producing F 4+ have been investigated with high-energy resolution, using the CRYRING heavy-ion storage ring. The absolute recombination rate coefficients are derived in the centre-of-mass energy range of 0−25 eV. The experimental results are compared with intermediate-coupling AUTOSTRUCTURE calculations for 2s−2p ( n = 0) core excitation and show very good agreement in the resonance energy positions and intensities. Trielectronic recombination with 2s 2 −2p 2 transitions are clearly identified in the spectrum. Contributions from F 5+ ions in an initial metastable state are also considered. The energy-dependent recombination spectra are convoluted with Maxwell-Boltzmann energy distribution in the 10 3 −10 6 K temperature range. The resulting temperature-dependent rate coefficients are compared with theoretical results from the literature. In the 10 3 −10 4 K range, the calculated data significantly underestimates the plasma recombination rate coefficients. Above 8 × 10 4 K, our AUTOSTRUCTURE results and plasma rate coefficients from elsewhere show agreement that is better than 25% with the experimental results.

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“…The limit of the C II 2s2pnl series was taken from [34] and the limit of the C III 2pnl series is from [35]. The lower excited states were calculated by a Rydberg formula in agreement with [36]. We note that the yield of electrons with kinetic energies < 1 eV is probably underestimated due to saturation at the center of the detector.…”

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confidence: 99%

Tracing transient charges in expanding clusters

Schütte¹,

Vrakking²,

Rouzée³

2017

Phys. Rev. A

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We study transient charges formed in methane clusters following ionization by intense nearinfrared laser pulses. Cluster ionization by 400 fs (I = 1 × 10 14 W/cm 2 ) pulses is highly efficient, resulting in the observation of a dominant C 3+ ion contribution. The C 4+ ion yield is very small, but is strongly enhanced by applying a time-delayed weak near-infrared pulse. We conclude that most of the valence electrons are removed from their atoms during the laser-cluster interaction, and that electrons from the nanoplasma recombine with ions and populate Rydberg states when the cluster expands, leading to a decrease of the average charge state of individual ions. Furthermore, we find clear bound-state signatures in the electron kinetic energy spectrum, which we attribute to Auger decay taking place in expanding clusters. Such nonradiative processes lead to an increase of the final average ion charge state that is measured in experiments. Our results suggest that it is crucial to include both recombination and nonradiative decay processes for the understanding of recorded ion charge spectra.The ionization of clusters by intense laser pulses induces highly complex dynamics that take place on attosecond to nanosecond timescales and that involve a large number of interacting particles. Intense lasercluster interactions commonly involve an ionization stage, the establishment of a nanoplasma and the subsequent expansion and break-up of this nanoplasma. Disentangling the different mechanisms is a very challenging task that requires sophisticated theoretical and experimental approaches. In spite of the large efforts that have been devoted to the study of laser-cluster interactions in the past 20 years (see e.g. [1-4]), the understanding of both the ionization and relaxation dynamics taking place during the cluster expansion are still far from being complete. For instance, up to now, experiments have only provided limited information about the relative importance of direct laser-induced (multi-photon and tunneling) ionization and electron-impact ionization by laserdriven electron-atom/ion collisions The development and application of pump-probe techniques promises novel insights into the relevant processes. For instance, the generation of seed electrons in a cluster by an extreme-ultraviolet (XUV) pulse allows the time-resolved investigation of strong-field processes induced by near-infrared (NIR) pulses [5]. Amongst the various processes that take place during the cluster expansion, electron-ion recombination processes are known to play an important role [1,3,[6][7][8][9]. Recently, recombination resulting in the production of a large number of excited atoms and ions was temporally resolved using pump-probe photoion and -electron spectroscopy [10][11][12], showing similar dynamics for clusters ionized by intense XUV and intense NIR pulses, respectively. These results suggest that the charge distributions that can be measured after the nanoplasma has expanded may differ significantly from the transient charge distributions ...

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Storage Ring Measurement of the CivRecombination Rate Coefficient

Cited by 108 publications

References 41 publications

Experimental dielectronic recombination rate coefficients for Na-like S VI and Na-like Ar VIII

Experimental dielectronic recombination rate coefficients for Na-like S VI and Na-like Ar VIII

Experimental rate coefficients of F⁵⁺recombining into F⁴⁺

Tracing transient charges in expanding clusters

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Storage Ring Measurement of the CivRecombination Rate Coefficient

Cited by 108 publications

References 41 publications

Experimental dielectronic recombination rate coefficients for Na-like S VI and Na-like Ar VIII

Experimental dielectronic recombination rate coefficients for Na-like S VI and Na-like Ar VIII

Experimental rate coefficients of F5+recombining into F4+

Tracing transient charges in expanding clusters

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Product

Resources

About

Experimental rate coefficients of F⁵⁺recombining into F⁴⁺