星野 正光

A new experimental technique for the measurements of the total cross section for electron scattering from atoms and molecules at very low energy is described. Momentum transfer cross sections for scattering from Ar, Kr and Xe at very low energies were carefully derived using the modified effective range theory from the recently measured total cross sections, which were obtained with a new experimental technique utilizing the threshold photoelectron source. A significant discrepancy between the momentum cross sections derived from the present analysis and those determined in the previous electron swarm studies was found at energies below 100 meV. The findings emphasize the need of further high precision experiments in the very low energy region as well as re-analysis of the previous swarm data.

An experimental technique for the measurement of the total cross section for electron scattering from atoms<br /> and molecules at high resolution is described. The total cross sections for electron scattering from Kr in the<br /> energy range from 14 meV to 20 eV obtained with the technique are also reported. The present technique<br /> employs a combination of the penetrating field technique and the threshold photoionization of rare-gas atoms<br /> using synchrotron radiation as an electron source in order to produce a high-resolution electron beam at very low<br /> energy. The characteristics of the electron sources were determined by measuring the ionizing photon energy<br /> dependence of photoelectron yield. Absolute total cross sections for electron scattering are obtained by the<br /> attenuation method. The measured absolute values of the total cross sections for electron scattering from Kr<br /> agree with those obtained by other groups down to 175 meV, above which several experimental works have been<br /> reported. Below 175 meV, the present results generally agree with theoretical cross sections down to 14 meV.<br /> The resonant structures in the total cross sections due to Kr− (4p55s2 2P3/2) and the Kr−