Nobuo Oda

Doppler profile measurements of balmer-α radiation by electron impact on H2☆

Abstract The profile of emission spectra of Balmer-α radiation by electron impact on H 2 has been investigated by using an etalongrating monochromator with high resolution ( * (3) resulting from the process, H 2 + e →H * (3)+H( a )+e, has two kinds of average kinetic energies; -0.3 eV and -7 eV. The angular and/or kinetic-energy distribution of H * (3), on which a spectral profile of Balmer-α radiation depends, is discussed in connection with the potential energy curve of the highly-excited states of the H 2 molecule.

Translational spectroscopy of electron-impact dissociative excitation of H2O and D2O by doppler profile measurements of Balmer-α emission

Abstract The Doppler profiles of Balmer-α emission by electron impact on H 2 O and D 2 O have been measured through varying the impact electron energy using an etalon-grating monochromator with a high-resolving power. The Doppler profiles consist of the two components, i.e., the narrow component and the broad one. This result implies that there are two kinds of precursors leading to H* (3) or D* (3) contributing to the Balmer-α emission. The average kinetic energies of H* (3) are (0.4 ± 0.2) eV and (4 ± 1) eV for the narrow component and the broad component, respectively, and are the same as those of D* (3) within experimental uncertainties. Discussions are given on the precursors of H* (3) and D* (3) contributing to the Balmer-α emission, the isotope effect on the kinetic energies of H* (3) and D* (3), and the ratio of the radiation intensity of the broad component to that of the narrow component.

Energy and Angular Distributions of Electrons from Atoms and Molecules by Electron Impact

Some experimental results on cross sections, differential in energy and angle, for electrons scattered or ejected from helium, methane, carbon monoxide, and water by intermediate-energy electron impact are presented, and the doubly differential cross section for helium is compared with theoretical calculations for models such as the scaled Born approximations with and without interference, the plane-wave Born approximation, the Born approximation with the Roothaan ground state wave function, and the binary encounter theory, resulting in a fairly good agreement between experiment and theory for the Born approximations except in the case of the plane-wave Born approximation. The experimental doubly differential cross sections are integrated over angles to derive the singly differential cross sections, differential only in energy, which are compared with the Mott cross sections corrected for binding energies of orbital electrons. Finally, the bearings of the measurement of doubly differential cross sections on the description of the track structure, the electron slowing-down spectra, the total ionization cross sections, and the stopping power for lower energy electrons are discussed. (auth)

A mechanism of the high frequency AC iontophoresis

The efficiency and the voltage dependence of the AC iontophoresis were studied in vitro. Two cylindrical glass cells separated by a cellophane film were used, where the donor cell was filled with the solution of target electrolytes and the receptor cell with distilled water. The sinusoidal AC voltage with a frequency of 1 kHz was applied between the two platinum plates located at the opposite ends of two cells. The time variation of the ion concentration was evaluated by measuring the impedance of the solution in the receptor cell. The transportation velocity of the ions increased with the amplitude of the voltage applied between two platinum plate electrodes apart 20 mm up to approximately 15 V, and leveled off above approximately 15 V. A theoretical model is proposed on the AC iontophoresis, where each ion moves together with the surrounding water molecules when it is hydrated. The effective Stokes radius of an ion is assumed to be half of the whole size of the ion with hydrating water molecules. When the external alternating electric field strongly vibrates the ion, the ion-dipole interactions between the ion and water molecules are broken, resulting in the reduced effective Stokes radius, which leads to the increase of the diffusion efficiency.

Translational spectroscopy of electron impact dissociation of molecules isoelectronic with Ne by doppler profile measurements of Balmer-α emission

Abstract The Doppler profiles of Balmer-α emission by electron impact on NH 3 and CH 4 have been observed at various electron impact energies by using a They are compared with those of HF and H 2 O previously reported. The kinetic energies of H * (3) have been determined from careful analysis of the excited states of these molecules, are discussed from the view point of these molecules being members of the neon isoelectronic sequence.

Energy and Angular Distributions of Secondary Electrons Resulting from Ionizing Collisions of Electrons with Helium and Krypton

Cross sections differential in angle and energy have been measured of secondary electrons resulting from ionizing collisions of electrons with helium at the primary energy E 0 =500 eV and 1 keV and with krypton at E 0 =1 keV. The total spectra, consisting of the continuum spectra due to direct ionizations and the sharp line spectra due to indirect ionizations (autoionizations or Auger processes), have been measured with an energy resolution of about 0.2 eV over the angular range from 10° to 130°. The continuum spectra are derived from the total spectra for electron energies from 25 eV to 45 eV for helium and from 24 eV to 52 eV for krypton and compared with the calculations by the binary encounter theory.

Experimental and theoretical studies of the effect of electrode polarisation on capacitances of blood and potassium chloride solution

The effects of electrode polarisation on the observed capacitances of electrolytic solutions, including whole blood, plasma and potassium chloride solution, have been investigated experimentally in the frequency region from 10 to 105 Hz, by varying the area of the electrodes using plate and mesh electrodes, by varying the electrode distance, and by varying the concentration of KCl in the potassium chloride solution. The effects of the electrode polarisation on the observed capacitances were most significant in the frequencies lower than 102 Hz, but cannot be neglected in any frequency region. The so-called α dispersion observed in the frequencies lower than about 103 Hz was reproduced theoretically with an equivalent circuit model, using constant values independent of frequency for the four circuit parameters: sample capacitance, sample conductivity, electrode polarisation capacitance and electrode polarisation conductivity. It was concluded that the observed α dispersion is not a real one that represents the specific features of the samples themselves, but an apparent one that represents the characteristics of the whole measurement system, including the electrode polarisation.

Simulation of doppler profiles of atomic radiation excited by molecular dissociation. The effect of population of magnetic sublevels

Abstract The Doppler profile of atomic radiation excited by electron-impact molecular dissociation has been simulated, where the population of dissociated atoms in magnetic sublevels has been considered as well as the kinetic energy and angular distributions. The results show that the Doppler profiles depend very strongly on the magnetic sublevel population.

Translational spectroscopy of electron impact dissociation of HF by doppler profile measurements of Balmer-α emission

Abstract The Doppler profiles of the Balmer-α emission by electron impact on HF have been investigated through varying the electron impact energy by using an etalon-grating monochromator with a high resolving power. The spectral profiles of the Balmer-α emission consist of three components, which indicates that there are three kinds of precursors leading to H*(3) contributing to the Balmer-α emission. The average kinetic energy of H*(3) is obtained for each component. From discussions on the precursors of H*(3) and their dissociation processes, the observed profiles have been ascribed to the dissociation of Rydberg states (≈18 eV), doubly excited states (≈23 eV) and inner shell excited states (≈40 eV).

Energy and angular spectra of electrons emitted from foils by ion beams

Abstract Energy and angular spectra of electrons emitted from carbon foils (4–20 μm/cm 2 ) have been measured for the angular range 20°–150° for H + , H 2 + , and H 3 + ions with energy 0.8 MeV/amu. Energy spectra consist of the high intensity low energy (⩽200eV) components and the relatively low intensity high energy ones with structure. Dependence on foil thickness and ion configuration, H + , H 2 + or H 3 + , have been investigated. It was found that the high energy components consist of carbon K Auger electrons, the charge transfer to continuum electrons, and the binary collision electrons in forward angles and, on the other hand, of carbon Auger electrons and electrons stripped from projectiles (H 2 + , H 3 + ) in backward angles.