Toshio Kusakabe

Electron Capture by C+, N+ and O+ Ions in Collisions with H2 Molecules and He Atoms at Low keV Energies

Electron capture cross sections for C + , N + and O + ions produced by controlled electron impact have been measured in collisions with H 2 and He targets at low keV energy region. It is found that the metastable state ions, if present, change significantly the observed cross sections and, in particular, the previously determined cross sections for C + ions colliding with H 2 targets are found to be mostly due to the metastable state ions instead of the ground state ions. More significant effects of the metastable state ions are observed in He targets.

Sensitivity Coefficients of Pirani Gauge for Various Atoms and Molecules

The sensitivity coefficients of a Pirani gauge in a constant voltage with bridge imbalance monitoring have been determined for various atoms and molecules. Except for light particles such as He atoms, H2 and D2 molecules, the observed coefficients show a strong correlation with the reduced thermal conductivities of free gas particles.

Charge-transfer processes in collisions of He{sup 2+} ions with H{sub 2}, N{sub 2}, O{sub 2}, CO, and CO{sub 2} molecules below 4 keV/u

Single- and double-charge-transfer cross sections of {sup 3}He{sup 2+} ions in collisions with N{sub 2}, O{sub 2}, CO, and CO{sub 2} molecules have been measured in the energy range of 0.20 to 2.7 keV/u. In addition, the same type of measurements for H{sub 2} molecules has been also carried out again for energies in the range from 0.13 to 0.40 keV/u. For all molecules except for CO{sub 2}, the present single-charge-transfer cross sections are found to be generally larger than, or at least comparable to, double-charge-transfer cross sections in the energy region studied. This is a marked difference in comparison to experimental results reported earlier where a sharp increase for double charge transfer was observed below 0.3 keV/u. The double-charge-transfer cross sections are found to be apparently larger than single-charge-transfer cross sections only for CO{sub 2} molecules at energies below 0.8 keV/u. A theoretical analysis based on a close-coupling method within a molecular representation has also been carried out for H{sub 2} and CO targets to provide some insights.