The proposed research focuses on the outstanding problem of electronic excitations in disordered molecular condensates, including amorphous semiconductors and glassy ionic systems. The microscopic nature of charge carriers and the interaction of electronic and structural excitations in these materials are fundamental problems that have been a subject of controversy and evaded quantitative explanation for decades. The lack of this microscopic understanding has limited our ability to employ disordered materials as economically viable alternatives to the more expensive crystalline compounds, in energy conversion and storage, and many other applications. Recent advances in the theory of the glass transition will provide the molecular basis for connecting the structural aspects of relaxations in amorphous materials and ionic melts with the underlying electronic transitions and ionic motions. A crucial new insight is that nearly degenerate structural transitions, which are intrinsic to quenched systems, give rise to the previously unexplained density of electronic states pinned at the middle of the forbidden gap. This microscopic picture will be further used to achieve quantitative understanding of trapping and recombination of charge carriers in electronic conductors. The proposed methodology will enable us to discriminate between ionic currents that are intrinsic to the amorphous structure, and currents that do not require structural transitions, as in superionic compounds, leading to first principles descriptions. In addition to providing new fundamental insights, elucidating the connection between electronic properties and the structural excitations will be a starting point for manufacturing disordered materials with tailored electronic and optical properties.
Arnold O. Beckman exemplifies the meaning of the word humanitarian. Combined with his unwavering enthusiasm for life, his keen sense of humor and his strong moral and ethical principles, he is a national icon.