Applications, molecular electronics contacts

Since his appointment at the University of Waterloo, Paldus has fully devoted himself to theoretical and methodological aspects of atomic and molecular electronic structure, while keeping in close contact with actual applications of these methods in computational quantum chemistry. His contributions include the examination of stability conditions and symmetry breaking in the independent particle models,109 many-body perturbation theory and Green s function approaches to the many-electron correlation problem,110 the development of graphical methods for the time-independent many-fermion problem,111 and the development of various algebraic approaches and an exploration of convergence properties of perturbative methods. His most important... 

The distinction between the two classes of materials considered in this Section per tains to the presence or absence of mixing at the molecular level. Thus in alloys, solid solutions of two or more semiconductors are formed where the lattice sites are interspersed with the alloy components. Semiconductor alloys, unlike their metallic counterparts, have a much more recent history and their development driver has been mainly optoelectronic (e.g., solid state laser) applications. In mixed semiconductor composites, on the other hand, the semiconductor particles are in electronic contact but the composite components do not undergo mixing at the molecular level. 

One successful application of STM beyond imaging has been the STM break junction (STM-BJ) technique [56] and modification thereof [13, 57, 58], which are becoming very popular experimental platforms for nanoelectronics and molecular electronics [59-61]. In this technique. Figure 9.5a, a tip (usually Au) is brought into mechanical contact to a defined depth (crash-to-contact) with a single-crystalline surface of the same material. The tip is then withdrawn at a suitable rate such that a metal nanoconstruction is formed, elongated, and eventually broken (break-of-contact). During tip withdrawal, the conductance is recorded as a function of piezo displacement. The procedure can be repeated many thousands of... 

The methodology of surface electrochemistry is at present sufficiently broad to perform molecular-level research as required by the standards of modern surface science (1). While ultra-high vacuum electron, atom, and ion spectroscopies connect electrochemistry and the state-of-the-art gas-phase surface science most directly (1-11), their application is appropriate for systems which can be transferred from solution to the vacuum environment without desorption or rearrangement. That this usually occurs has been verified by several groups (see ref. 11 for the recent discussion of this issue). However, for the characterization of weakly interacting interfacial species, the vacuum methods may not be able to provide information directly relevant to the surface composition of electrodes in contact with the electrolyte phase. In such a case, in situ methods are preferred. Such techniques are also unique for the nonelectro-chemical characterization of interfacial kinetics and for the measurements of surface concentrations of reagents involved in... 

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