Y Kaneko

Mobilities of Ne^+ and Ar^+ Ions in He Gas at 82 K

Mobilities of Ne + and Ar + ions in He gas were studied at 82 K. An injected-ion drift tube mass spectrometer, the drift tube of which can be cooled with liquid nitrogen was developed for this purpose. The mobility curves obtained have a bump at intermediate E / N , and the zero-field reduced mobilities have approached to the polarization limits. The He peculiarities which have been known for long time are explained clearly by the temperature effects found in this work.

A Charge Transfer Mechanism between a Rare Gas Ion and a Diatomic Molecule; the Implication of Inner-Shell Level Mixing

A new mechanism for charge transfer is presented in order to interpret the low-energy experimental results for Ar + +O 2 →Ar+O 2 + and Kr + +O 2 →Kr+O 2 + collisions. A collision complex is formed by the coupling of the outermost orbital of an Ar + (or Kr + ) and the inner O 2 -π u orbital due to the proximity of their binding energies. A further electronic transition takes place from this charge-transfer state to the O 2 + ground state during the formation of the collision complex. The possibility of this mechanism is theoretically considered and the consistency of the present mechanism with the data for Ar + +NO, Kr + +NO, and Ar + +CO collisions is also discussed.

Gain characteristics of a microchannel plate and a channel-electron multiplier for low energy multiply charged ions

Abstract Pulse height distribution are measured when multiply charged ions of S, Ne, F, O, N and C are incident on a microchannel plate of chevron type (MCP) and a channel electron multiplier (CEM) in the velocity range of 3–4.5 × 105 m/s. The pulse height distributions obtained with the CEM shows no significant dependence of the gain on the energy, mass and charge state of incident ions. On the other hand, for the case of the MCP, an increase of the gain is observed with an increase of the charge state of incident ions irrespectively of ionic species. Such behavior is discussed in connection with secondary electron emission yield at the input and electron multiplication mechanism iin the channels.

Electron capture processes of Iq+ ions with very high charge states (41⩾q⩾10) in collisions with He atoms

One-electron capture processes of iodine (Iq+) ions with very high charge q up to 41 in collisions with He atoms at low energies have been investigated using energy gain spectroscopy. It is found that total cross sections increase with increasing charge of ions q, and also increase roughly with the square of the crossing radius Rc of the diabatic potential curves in the quasi-molecules where the electron transfer takes place. This smooth variation, in contrast to that in ions with low charge where only few crossings play a role, can be understood from the fact that a number of the crossings closely located in a relatively narrow region of Rc contribute to the one-electron transfer processes in ions with high charge.

Observation of electron capture into selective state by fully stripped ions from He atom

Energy spectra of charge-changing projectile ions are measured for one-electron capture by fully stripped C and O ions from He atoms. The electron is selectively captured into a single level of principal quantum number n=3 of C5+ and n=4 of O7+, respectively, at a collision of 0.45 KeV amu-1.

The (n,l) distributions in electron capture reactions for C3+, N4+ and O5+ ions colliding with He

Distributions of captured electrons in the reaction Aq++He to A(q-1)+(n,l)+He+ over the final-state quantum numbers n and l are measured using a beam spectroscopy method at the energy of 1.0q keV. Projectile ions Aq+ are Li-like species of carbon (q=3), nitrogen (q=4) and oxygen (q=5).

Electron capture in Iq+ (q = 10–41) + He collisions at low energies

One electron capture processes in Iq+ (q = 10–41) +He collisions at low energies have been investigated. It is found that total cross sections for one-electron capture processes increase roughly linearly with increasing charge q of the incident ions and also increase with the square of the crossing radius Rc of the diabatic potential energy curves where the electron transfer takes place. These smooth increases are in contrast to those observed for ions with low charge q < 10.

The dependence of Rc of cross sections for one-electron capture by S11+, S13+ and Krq+ (q=7-25) ions from He atoms

Total cross section measurements and translational energy spectroscopy have been performed at collision energies of 1q keV for one-electron capture processes by S11+, S13+ and Krq+ (7<or=q<or=25) ions from He atoms. When the measured cross sections are plotted as a function of the crossing radius Rc deduced from the observed energy gain, it is found that the cross sections in general increase with Rc and almost all of them lie between the 1/2 pi Rc2 and pi Rc2 curves. This dependence on Rc is very different from previous results for ions with relatively low q(q<10).