1. INTRODUCTION

Several directions may be identified is studies of the effects of ionizing radiation on particles in suspension. The first one is simply to understand the consequences of irradiating a multi-phase system.1 ^,2 Would the energy be confined into one phase or the other? How much energy or charge is transferred across the interface and what fraction remains arrested in each of the phases? Does the interface, its composition and the surface charge alter the outcome of the chemistry? In another direction ionizing radiation is used as a synthetic tool to prepare particle suspensions. Many metallic particles and a few semiconductors as well, were prepared using this approach. ^{3 6} The advantage of using radiolytic approach over wet chemical methods is the ability to control the size and size distribution by controlling the dose-rate delivered to the precursors solution. A third direction focuses on mechanistic studies conducted on suspensions of nanoparticles. The suspensions allow time domain optical measurements, which are common in radiation research, and therefore are often utilized to study mechanisms of short-lived intermediates generated in the suspensions. In this report we survey mostly recent observations from the first area of activity: transfer of energy or charge initially generated by ionizing radiation in one phase into the other.

Interfacial processes induced by ionizing radiation are of interest as a fundamental scientific question, as well as a technologically relevant concern. When high-energy particles travel through a multiphase system, ionization and excitations occur at each of...