A Danjo

Elastic Scattering of Electrons from H2O Molecule

Elastic differential cross sections (DCSs) for H 2 O have been measured in the energy range from 4 to 200 eV and in the angular range from 10° to 120° by a crossed beam method. The absolute scale of the DCSs was given by normalizing the relative values to the absolute elastic DCSs for He with the relative flow method. Integral and momentum transfer cross sections were derived from the DCSs and compared with the previous experimental and theoretical results.

Differential Cross Section of Electron Scattering from Molecular Hydrogen. II. b3Σu+ Excitation

Differential cross section(DCS) for the electron-impact H 2 (b 3 Σ u + ) excitation has been measured in the incident energy range from 12 to 60 eV and in the angular range from 10° to 130°. The electron transmission efficiency of the energy analyzer was calibrated using the secondary electron emission cross sections from N 2 molecule. The inelastic DCS is normalized to the absolute H 2 elastic DCS. Integral cross section is derived from the measured DCS. Measured DCS is compared with other experimental and theoretical results.

Differential Cross Sections of Electron Scattering from Molecular Hydrogen I. Elastic Scattering and Vibrational Excitation (X1Σ+g, v=0→1)

Differential cross sections (DCSs) for the elastic scattering and the vibrational excitation of molecular hydrogen by electron impact have been measured in the energy range from 2.5 eV to 200 eV and in the angular range from 10^° to 120^°. Absolute values of the DCSs are obtained by normalizing the relative values to the absolute elastic DCSs for He by means of the relative flow method. Integral and momentum transfer cross sections for each scattering process are also given. Differential, integral and momentum transfer cross sections obtained in the present measurements are compared with the previous experimental and theoretical results.

A scaling law of cross sections for multiple electron transfer in slow collisions between highly charged ions and atoms

A simple scaling relation is derived for the partial and total multiple-electron capture cross sections in slow collisions of highly charged ions with atoms based on the extended classical over-barrier model. It is shown that the currently available experimental cross sections are reproduced quite satisfactorily by this relation.

Electron impact ionization of O+, S+ and S2+ ions

Absolute cross sections for electron impact single ionization of O + , S + and S 2+ ions have been measured at an electron impact energy range from below threshold to 1000 eV, using the crossed beam technique. The measured cross sections for O + ions are reproduced quite well with the semiempirical Lotz formula over the whole energy range investigated. The measured cross sections for S + and S 2+ ions show a more rapid rise from the threshold to their peak than those expected from the Lotz formula. For S 2+ ions, another small bump beginning at 120 eV is observed, where no level exists that may contribute to any direct or indirect ionization processes.

Electron Impact Ionization of C + , N + and P + Ions

Absolute cross sections for electron impact ionization of C + , N + and P + ions have been measured for electron energies from threshold up to 1000 eV, using the crossed beam technique. The measured cross sections for both C + and N + ions are in good agreement with the semiempirical Lotz formula over the whole energy range investigated, and also with those previously reported except for near threshold. The results for P + ions show a more rapid rise from the threshold and larger values around the peak than those calculated with the Lotz formula.

Electron Inpact Single Ionization of Ne2+, Ar2+, Kr2+ and Xe2+ Ions

Absolute cross sections for electron impact single ionization of doubly charged rare gas ions, Ne 2+ , Ar 2+ , Kr 2+ and Xe 2+ , have been measured in the energy range from below threshold to 1000 eV. The measurements were performed with crossed electron and ion beam technique. The measured cross sections for Ne 2+ ions are found to be in good agreement with the semiempirical Lotz formula for direct ionization. For Ar 2+ ions is found a small discrepancy between the observed cross section and the formula at lower energies. For Kr 2+ and Xe 2+ ions the measured cross sections exhibit complicated structures from threshold to medium energy and are significantly larger than estimates for the direct ionization. These enhancements and complex structures are believed to be indirect ionization processes, such as excitation-autoionization.

On the Altitude Dependence of the Atmospheric X-Rays in the Energy Range 0.1-1 MeV

It is pointed out that balloon observations so far reported on the finite flux of diffuse cosmic X-rays with energies greater than 0.2 MeV are subject to the procedure of subtracting the contribution of atmospheric X-rays. The transport of photons generated in the atmosphere was followed by a Monte Carlo calculation. It is found that energy-degraded photons generated at greater depths cause a build-up effect and flatten the intensity vs depth relation, the growth curve, of omnidirectional atmospheric X-rays at depths smaller than 10 gcm -2 . The present calculation can explain the behaviour of the observed growth curves. Thus, it is concluded that the assumption, adopted in some of the reports, that the growth curve is represented by a power function of the atmospheric depth is not valid. The present result demonstrates that the observations thus far have given only an upper limit of the cosmic X-rays flux above 0.2 MeV.It is pointed out that balloon observations so far reported on the finite flux of diffuse cosmic X-rays with energies greater than 0.2 MeV are subject to the procedure of subtracting the contribution of atmospheric X-rays. The transport of photons generated in the atmosphere was followed by a Monte Carlo calculation. It is found that energy-degraded photons generated at greater depths cause a build-up effect and flatten the intensity vs depth relation, the growth curve, of omnidirectional atmospheric X-rays at depths smaller than 10 gcm -2 . The present calculation can explain the behaviour of the observed growth curves. Thus, it is concluded that the assumption, adopted in some of the reports, that the growth curve is represented by a power function of the atmospheric depth is not valid. The present result demonstrates that the observations thus far have given only an upper limit of the cosmic X-rays flux above 0.2 MeV.

Target dependence of multi-electron processes in Iq+ (q=10, 15)+rare gas (Ne, Ar, Kr and Xe) collisions

We have determined experimentally the absolute cross sections for i-electron capture (to projectile) and j-electron removal (from target) ( sigma q,q-ij), total electron capture ( sigma q= Sigma i sigma q,q-i), j-electron removal ( sigma qj= Sigma i sigma q,q-ij) and i-electron capture ( sigma q,q-i= Sigma j sigma q,q-ij) for the processes: Iq+(q=10 or 15)+B to I(q-i)++Bj++(j-i)e (B identical to Ne, Ar, Kr and Xe) at collision energy of 1.5q keV. Charge-state distributions of the scattered ions were measured in coincidence with the recoil ions. The absolute electron-capture cross sections were measured by the initial growth-rate method. The experimental results for sigma q and sigma qj were compared with the predictions of the extended classical over-barrier model (ECBM). The branching ratios of the multiply-excited ions produced by multi-electron transfer have also been determined.

Electron spectroscopy of doubly-excited helium-like ions

Ejected electrons from helium-like doubly-excited carbon and boron ions, produced by C6+ and B5+ with He collisions, were measured by the zero-degree electron spectroscopy technique. Electrons from configurations 21nl were observed in a wide energy range.