Double Translational Energy Spectroscopy Research Articles

Charge Transfer in Ionic and Molecular Systems

first_page settings Order Article Reprints Font Type: Arial Georgia Verdana Font Size: Aa Aa Aa Line Spacing:    Column Width:    Background: Open AccessEditorial Charge Transfer in Ionic and Molecular Systems by Marie-Christine Bacchus-Montabonel Laboratoire de Spectrométrie Ionique et Moléculaire, UMR 5579, CNRS et Université Lyon I, 43 Bd. du 11 Novembre 1918, 69622 Villeurbanne Cedex, France Int. J. Mol. Sci. 2002, 3(3), 114; https://doi.org/10.3390/i3030114 Received: 5 February 2002 / Published: 28 March 2002 (This article belongs to the Special Issue Charge Transfer in Ionic and Molecular Systems) Download Download PDF Download PDF with Cover Download XML Download Epub Versions Notes Charge transfer reactions are fundamental processes present in almost all areas of physics, chemistry and biochemistry. Most of the time, these reactions are taking place in the condensed phase and solvent effects are determinant. Nevertheless, studies in the gas phase provide direct understanding of the intrinsic behaviour of the ions and are essential for the modeling of more complex mechanisms.Investigations of charge exchange reactions in ion-atom, ion-molecule and, more recently, ion-ion collisions are of fundamental as well as of practical interest. These reactions are of great importance in a variety of research fields, such as the description of many astrophysical and terrestrial environments, controlled thermonuclear fusion or ion accelerator technology. For example, the interaction of solar wind ions with cometary gases, auroral ions with planetary atmospheres, and stellar wind ions with the interstellar medium involves the formation of excited states of collision partners with the resultant visible, UV an X-ray emission. Both description of thermal and ionization balance of astrophysical plasmas and modeling of ion transport and radiative cooling processes in the diverter region of current large Tokamak fusion plasma devices require information on the relevant electron capture processes.Experimental methods such as single and double translational energy spectroscopy, energy gain spectroscopy, photon spectroscopy, Auger electron spectroscopy or recoil ion momentum spectroscopy combined with theoretical approaches, from the classical trajectory Monte-Carlo model, or the simple Landau-Zener model, to very accurate atomic or ab-initio molecular expansion methods within either time-dependent or time-independent collisional treatments, provide efficient tools for these studies. A large survey of these approaches is presented in this special issue, emphasizing recent results and developments of single-electron capture processes as well as multiple-electron capture reactions, essentially double-electron capture with regard to the complexity of the many-body problem involved, on ion-atom and ion-molecule collisions in the low-energy regime. Share and Cite MDPI and ACS Style Bacchus-Montabonel, M.-C. Charge Transfer in Ionic and Molecular Systems. Int. J. Mol. Sci. 2002, 3, 114. https://doi.org/10.3390/i3030114 AMA Style Bacchus-Montabonel M-C. Charge Transfer in Ionic and Molecular Systems. International Journal of Molecular Sciences. 2002; 3(3):114. https://doi.org/10.3390/i3030114 Chicago/Turabian Style Bacchus-Montabonel, Marie-Christine. 2002. "Charge Transfer in Ionic and Molecular Systems" International Journal of Molecular Sciences 3, no. 3: 114. https://doi.org/10.3390/i3030114 Find Other Styles Article Metrics No No Article Access Statistics For more information on the journal statistics, click here. Multiple requests from the same IP address are counted as one view.

State-selective one-electroncapture by slow state-prepared N2+(2P)ground-state ions in collisions with hydrogen atoms

The technique of double translational energy spectroscopy (DTES),recently successfully developed in this laboratory for use with targets ofatomic hydrogen, has been used to study one-electron capture byground-state N2+(2s22p)2Po ions in collisions with hydrogenatoms at energies within the range 0.8-6.0 keV. Cross sections for theformation of the main excited product channels have been determined. Themeasurements allow a re-evaluation of our previous TES measurementscarried out with N2+ primary beams containing an admixture ofmetastable N2+(2s2p2)4P ions. The main findings of theseearlier measurements are confirmed and the DTES measurements nowremove any ambiguity in interpretation of the experimental data. Whilerecent theoretical studies correctly predict the two main N+3Do and 3Po product channels, the quantitativeagreement with experiment is only partially satisfactory.

State Selective Electron Capture by State Prepared Beams of Multiply Charged Ions in Atomic Hydrogen

State selective electron capture by state prepared ground state ions of C2+, N2+ and O2+ in collisions with atomic hydrogen has been studied in the energy range 1.5–6 keV using the technique of double translational energy spectroscopy. In the case of C2+/H system it is clear from this comparison that whilst experiment and theory agree that the C2+(2s2p2) 2D state is the dominant product state there are considerable differences for the other C2+ product states. For the N2+/H system the experimental measurements confirm the predicted dominance of N+(2s2p2) 3Do formation but show that significant yields of other product states are formed. The only significant O+ product state resulting from the one-electron capture process by ground state O2+ 3P with H at 6 keV is O+ (2s2p4) 4P confirming theoretical calculations.

Excited state formation in studies of electron capture by state prepared doubly charged atomic ions

Electron capture by slow ( v < 1 a.u.) partially stripped ions in atomic and molecular targets results in the selective formation of only a few excited states of either target or projectile and is highly sensitive to the internal energy carried by the projectile. This article describes a new experimental system employing the technique of double translational energy spectroscopy to study these state selective electron capture processes. Recent results involving slow C 2+, N 2+, and O 2+ primary ions in prepared ground or metastable states, in collisions with simple atomic and molecular targets, are discussed. The results highlight the difficulties involved in the interpretation of previous studies where the projectile primary ion beams contained unknown mixtures of ions in both ground and metastable states.

Studies of state-selective electron capture using double translational energy spectroscopy

An apparatus developed in this laboratory which utilises double translational energy spectroscopy (DTES) is being used to study state-selective electron capture by state-prepared multiply charged ions. This experimental approach avoids the ambiguities inherent in many previous measurements carried out with primary ion beams containing unknown fractions of metastable ions. In this review, the effectiveness and future potential of DTES is illustrated by a discussion of some recent measurements of one-electron capture by 1S ground state and 3P metastable C2+ ions and by 2P ground state N2+ ions in collisions with a number of different gas targets.

Low Energy Electron Capture Studies with State-Prepared Multiply Charged Ions

State-selective one-electron capture involving pure beams of 3P ground state and 1D metastable O2+ ions has been investigated by Double Translational Energy Spectroscopy. Measurements have been made in which the relative importance of the excited product channels are established without the ambiguity inherent in earlier Translational Energy Spectroscopy measurements.

State Selective Electron Capture Studies with Slow State Prepared Ion Beams

Double translational energy spectroscopy has been successfully used to study state selective electron capture processes in atomic and molecular targets involving slow (v < 1 au) C2+, N2+ and O2+ primary ions in prepared ground or metastable states. The results show that previous TES and total one electron capture measurements involving primary ions beams containing unknown fractions of metastable states require cautious interpretation.

State-selective one-electron capture by ground-state ions in slow collisions with He, Ne and Ar using double translational energy spectroscopy

Double translational energy spectroscopy (DTES) has been used to study state-selective one-electron capture by pure ground-state ions in collisions with He, Ne and Ar at energies within the range 1.75 - 8.0 keV. The main collision channels have been identified and their relative importance has been assessed quantitatively. These measurements avoid the ambiguities inherent in the interpretation of previous TES measurements carried out using primary ion beams containing unknown fractions of metastable ions. In the absence of any detailed theoretical studies, we have calculated Landau - Zener reaction windows for these processes and shown that they accommodate the observed collision channels with limited success.

State-selective one-electron capture by 4 keV ground state and metastable ions in collisions with and

The technique of double translational energy spectroscopy (DTES) has been used in a recently developed apparatus to study (for the first time) one-electron capture by state-prepared ions in collisions with and molecules. These processes are relevant to astrophysical situations, planetary atmospheres and to the modelling and diagnostics of edge plasmas in current fusion devices. The main collision channels resulting from state-selective electron capture by pure beams of 4 keV ground state and metastable ions have been separately identified and their relative importance determined without any of the ambiguities inherent in TES studies normally carried out with ion beams of unknown metastable content. At the energy considered, only non-dissociative electron capture is observed with collision channels involving capture into the and states together with the formation of and in ground and electronically excited states. Our measurements indicate that some of these molecular ions have significant degrees of vibrational excitation in accord with the Franck - Condon factors for the relevant transitions. Striking differences between the collision channels for ground and metastable ions are observed.

Production of state-prepared beams of multiply charged ions for studies of state-selective electron capture collisions

A new apparatus which utilizes double translational energy spectroscopy (DTES) is described. This allows studies of state-selective electron capture by multiply charged ions in well defined states. This approach avoids the ambiguities inherent in the results of many previous measurements carried out with beams containing metastable ions. The considerable potential of DTES has been illustrated by measurements of one-electron capture by C2+ ions in collision with Ar at 4 keV.

State-selective electron capture by 4 keV state-prepared beams of ground state and metastable C2+ ions

A new apparatus employing double translational energy spectroscopy has been used to study state-selective electron capture by 4 keV beams of pure 1S ground state and pure 3P metastable C2+ ions in collisions with He and H2. In each case the main excited product channels have been unambiguously identified and their relative importance established.

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

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.