Papers by Author: Hideoki Murakami

Abstract: Positron lifetime spectroscopy was conducted for natural minerals to investigate open-nano pores. Positronium (Ps) formation occurs with ortho-positronium (o-Ps) intensities ranging from a few % to 20 % and size distributions of nano pores are evaluated from o-Ps lifetimes. The results will be discussed with respect to formation processes of nano pores influenced by earth's environment.

Abstract: Age-momentum correlation (AMOC) spectroscopy, which can sensitively probe momentum distributions of positrons and positronium (Ps), was conducted for studying the pick-off process of the triplet bound state ortho-Ps (o-Ps) with electrons at the walls of the free volume holes. Influences of different chemical elements forming free volume and the size of the free volume are investigated. It is found that the momentum distribution of o-Ps pick off annihilation sensitively depends on the electronic state. The feasibility of the chemical analysis relevant to the free volume in insulating materials is discussed.