Abstract: The 15N chemical shifts of a number of polyazaindenes have been determined, and have been correlated with the degree of contribution to the ground state of those resonance structures which place a partial positive charge on the bridge-head nitrogen.

Abstract: The macroscopic dynamic theory of partial charge transfer processes on semiconductor surfaces and electrodes which is relevant for several electrochemical, photochemical and catalytic phenomena, has been corroborated on the basis of quantummechanical model calculations. In this paper, the quantummechanical foundation of partial charge transfer coefficients of «w-type (which belong to the space charge layer subsystem) is considered under electronic equilibrium condition for semiconductor/gas and semiconductor/electrolyte interfaces. For processes on semiconductor electrodes, the relation of /»-coefficients to partial charge transfer coefficients ). and I of the interface subsystem and to partial charge injection into the space charge layer has been formulated. The requirements for calculating electronic nonequilibrium of the space charge layer are briefly outlined and cases with complete suppression of electron transport considered.

Abstract: Huheey's approach to the calculation of partial charges on groups is extended and some group electronegativity parameters modified. The modified form of Huheey's method is shown to provide rapid access to net group charges (population numbers) in cations, radicals, anions, and sulfur trigonal bipyramids. Results obtained by substituent electronegativity calculations are shown to be comparable to those obtained by abinitio calculations.

Abstract: Single crystal sections of HgI/sub 2/ (about 1 cm thick) have been evaluated for charge carrier transport properties. Using these thick detector structures, surface effects produced during fabrication are reduced, enhancing the bulk property characteristics. The standard time-of-flight method was used to determine electron and hole mobilities. Lifetime measurements for electrons and holes were made by direct observation of the carrier decay where crystal transit times were long compared to lifetimes. Nonlinear charge carrier velocities have been observed during mobility measurements. These nonlinearities impair a partial charge collection technique for spectra generation taken with thick detectors while having a lesser effect on the standard full charge collection approach. Partial charge collection methods have produced greater peak efficiencies than full charge collection, and investigations of crystal properties are being used to enhance this method.

Abstract: An application of the time-dependent Hartree-Fock (TDHF) theory of charge transfer in atomic collisions is presented. Probabilities for elastic and double symmetric charge exchange are calculated for a fixed laboratory scattering angle and for collision energies from 10 to 70 keV. The TDHF equations are solved using finite difference techniques and propagated in time using the Peaceman-Rachford alternating-direction implicit method. Plots of time-evolved charge densities are presented also.