Local structures and motions of radical reactants in highly selective tunneling abstraction reaction in neopentane-ethane mixture are investigated with CW-ESR, ENDOR, and ESEEM spectroscopy at different temperatures. H atoms produced by the radiolysis of neo-C 5 H 12 in the neo-C 5 H 12 -C 2 H 6 (2 mol %) mixtures above 40 K react selectively with the solute C 2 H 6 to give ethyl radicals. The selective reaction is suppressed below 30 K. The local structures of neopentane matrix around neopentyl and ethyl radicals are approximately the same in the temperature range from 4.4 to 45 K. Although neopentyl radicals are rigidly trapped below 100 K, ethyl radicals in neopentane matrix begin to librate even at 6 K and increase the degree of motion up to 30 K. Finally, the librating motion of the ethyl radicals in neopentane matrix is vigorous above 40 K. The ethane molecule can take more favorable orientation for the hydrogen abstraction reaction by H atoms than rigid neopentane molecules by the vigorous libration motion, resulting in the selective reaction with H atoms.

The solid solubility of Cu in A1 under pressure is studied using the microscopic electronic theory. An increase of the solubility up to 10 at% Cu in A1 is predicted under a pressure of 10 GPa. The obtained results for the lattice constant, the heat of solution, the pressure-volume relation, and elastic moduli in the Al-Cu system are presented theoretically.Die feste Loslichkeit von Kupfer in Aluminium unter Druck wird mit Hilfe der mikroskopischen Elektronentheorie untersucht. Die Ergebnisse zeigen eine Zunahme der Loslichkeit bis zu 10 At% Kupfer in Aluminium unter einem Druck von 10 GPa. Die berechneten Daten fur die Gitterkonstante, die Losungswarme, die Druck-Volumen-Relation und die Elastizitatsmodule in der AluminiumKupfer-Legierung werden theoretisch angegeben.

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