Ryoichi Ono

Structural Alteration of Nanostructure Carbon Particles Carrying Pt Clusters in H2 and O2 Gases

The effects of H2 and O2 gases on the typical fuel cell catalyst of Pt clusters on carbon particles (Pt on C) were examined using a special side-entry sample holder for high-resolution transmission electron microscopy. The holder can be used to transfer the specimen without exposure to air. The effects of H2 and O2 were detected after the specimen was exposed to the gases at 60 °C for 15 h. The predominant effect of H2 was the coagulation of the Pt clusters. The effect of O2 was to alter the structure of the carbon particles by oxidation.

Absorption of high energy electrons in liquid medium

Abstract The maximum range-energy relation for high energy electrons penetrating water is obtained based on a physical concept of the range for energetic particles. In this work, the deposited electrons in a liquid are measured with a sensitive electrometer by the charge collecting method. The absorption curve obtained in this method is free from the background due to bremsstrahlung, differing from the ion chamber method. Hence, in the high energy region the extrapolated range of water is shorter than that obtained from the ion chamber method. The maximum range in water in the present experiment agrees well with the theoretical evaluation obtained by the Monte Carlo method. The influence of the bottom of the container holding the absorber is so important that it is discussed experimentally.

Growth of Functional FeTi Clusters Covered with Carbon Layer

FeTi clusters with a diameter of less than 10 nm and covered with a graphitic layer have been preferentially produced in an H2 gas atmosphere at pressures of 10 and 26.6 kPa by the simultaneous evaporation of Fe and Ti wires from a concave carbon boat. To compare this result with cluster formation in an inert gas atmosphere, the result for an Ar gas pressure of 10 kPa is also discussed. The formation of disordered FeNi clusters predominately took place in an H2 gas atmosphere.

Absorption of high energy electrons in liquid nitrogen

Abstract The maximum range-energy relation for electrons of 4–32 MeV in liquid nitrogen is obtained by measuring the deposited electrons in the nitrogen with the use of a fine sensitive electrometer, as mentioned previously 1 ). Applying the previous method to the low temperature liquid absorber, we find that the measured maximum range in liquid nitrogen is rid of the influence from bremsstrahlung photons. By comparing the inclination of the maximum range-energy relation for liquid nitrogen with that for water, it is found that the former is greater than the latter, that is, the energy dissipation for liquid nitrogen is smaller than that for water.