Displacement of metal atoms from salts by hydrogen and the role of this reaction in chain processes

The interaction of hydrogen atoms with a variety of alkali metal and alkaline-earth metal salts results not only in the recombination of these atoms but also in the displacement, into the gas phase, of free radicals (CaCl^·(A ¹ P _1/2, B ² S ⁺) and CaF^·(A ² P)) and metal atoms, including their excited species, which are detected spectroscopically. Transmission spectra indicate that the NaCl surface undergoes metallization when treated with a high-frequency discharge and a rarefied hydrogen flame. Combustion is affected by the gas-phase hydrogen atoms involved in the chain reaction and by the varying composition and properties of the surface. The concentration of Na atoms over the NaCl surface at 770 K is 10⁹?10¹¹ cm^?3 in a stream of H atoms at 1 Torr and in the 2H₂ + O₂ flame at 4 Torr. The concentration of sodium atoms in the ² P _3/2 and ² P _1/2 excited states is ～5 × 10⁶?5 × 10⁸ cm^?3. The role of the discovered reactions in combustion, pyrolysis, and plasma chemistry is discussed.     

Medium energy ion scattering spectroscopy: Study of germanium amorphization under ion irradiation

An experimental setup for medium energy ion scattering spectroscopy allowing materials elemental composition diagnostics has been developed. A target composed of single-crystalline Ge with a smooth surface and structural inhomogeneity several nanometers thick has been prepared for conducting the experiments. Experiments have shown that the depth resolution of the method was 6 Å.     

Measurements of angular distributions of sputtered material as a new tool for surface-segregation studies: Segregation in CuPt alloys

The angular distribution of copper and platinum sputtered by argon ions from polycrystalline CuPt targets at 77 K has been measured by a collection technique. The argon-ion energy has been varied from 1.25 to 320 keV. For bombardment energies above 20 keV, differences in the angular distributions for the two elements indicate a strong copper segregation to the surface during bombardment.     

The modes of combustion of copper nanopowders

It was shown that the synthesis of Cu nanopowder by thermal decomposition afforded chemically purer (without oxides) and finer (specific surface value ～45 m2 g^?1) product than the synthesis by chemical reduction. The latter method leads to pyrophoric nanopowders containing detectable amounts of copper oxides.     

Exchange Processes in Pb(II) Complexes

A novel technique of 2D exchange NMR with suppression of the coherent magnetization transfer is suggested for the collection of useful chemical information on the basis of standard 2D exchange spectroscopy. In this technique, only one nucleus of the coupled spin system involved in chemical exchange is excited (so-called multiplet selectivity or semiselective excitation). In this case, the multiplet structure of the selectively irradiated nucleus behaves as an uncoupled multisite system.