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Pure Appl. Chem., 2009, Vol. 81, No. 1, pp. 45-60

Nanometer-scale dynamics of charges generated by radiations in condensed matter*

Akinori Saeki and Seiichi Tagawa

The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan

Abstract: The dynamics of short-lived charges generated by pulsed radiations such as electron beam (EB) and photon was investigated to elucidate their reactivity, electronic properties, and spatial behavior on a nanometer scale. Chemical reactions of radical cations (hole) and anions (electron) in condensed matter (organic liquids, polymers, and conjugated materials) occupy an important place in postoptical nanolithography and organic electric devices. The spatiotemporal evolution of charges during geminate ion recombination was measured by a highly improved picosecond (ps) pulse radiolysis and incorporated into a Monte Carlo simulation to clarify the key role of the charges in the formation of latent image roughness of chemically amplified resists (CARs). The dynamics and alternating-current (AC) mobility of transient charge carriers in conjugated materials such as polymer and organic crystals were studied by the combination of microwave conductivity and optical spectroscopies, revealing the potential plausibility for high-performance electric devices. Anisotropy measurement and methodology to resolve the sum of mobility into hole and electron components without electrodes have also been demonstrated.
*Pure Appl. Chem. 81, 1-84 (2009). A collection of invited, peer-reviewed articles by the winners of the 2008 IUPAC Prize for Young Chemists.