High-efficiency conversion of the electronic excitation energy to the translational degrees of freedom in collisions of excited atoms with the surface of a solid

An experimental study is reported about the quenching of electronic excitation of Cs atoms caused by their collisions with a glass surface. The energy with which they are scattered from the surface after quenching has been measured to be 0.5 eV, which is about one-third of the excitation energy. A discussion is given of the mechanisms by which the excitation energy is partitioned between the atom and the surface in two different cases, namely, in the excitation of the atom adsorbed on the surface and in the collision of the preexcited atom with the surface.     

Plastic flow at a crack tip. Energy failure criterion and its relationship to the J integral

Plastic flow at the tip of a crack moving in an elastic body is considered using the theory of an ideally rigid-plastic body. The material at the crack tip is treated as a body consisting of an elastic outer region and a rigid-plastic inner region. It is shown that this representation is energetically justified for small plastic regions. The distribution of the specific dissipation of the work of internal forces and deformations along the particle trajectory at the crack tip is obtained. The relationship between the specific dissipation of the work of internal forces and the J integral under plane-strain conditions is established.     

Optical method for measuring structural parameters of island films

An optical method for determining characteristics of the submicron structure in island films is proposed. The method is based on the measurements of fluctuations of optical properties of a film detected when a focused laser beam is scanned over it. It is shown that the island size distribution can be determined in principle by the method proposed. Structural inhomogeneity of a Cs film on sapphire is revealed experimentally. Parameters of these inhomogeneities are measured as functions of the film thickness. The correspondence of the results of the optical method and the data of electron microscopy is tested for a In film on glass.     

Bound diffusion of ultrafine particles in generalized anharmonic potential

Bound diffusion of ultrafine particles of ferric hydroxide precipitated inside the polymeric cross-linkage degree the experimental spectra reveal a striking broadening up to hundreds of mm/s. This is a consequence of the crossover from the diffusion of a Brownian oscillator to free diffusion in restricted volume, the spatial displacements of the particles depending on the cross-linkage and changing from 0.1 to 0.6 Å.     

Synthesis and mechanism of the formation of bis(methylamides) of pyrazoledicarboxylic acids

The reaction of ethoxymethyleneoxaloacetic ester with phenylhydrazine and methylhydrazine has been studied. It has been established that the addition of phenylhydrazine takes place to the ethoxy group through the -nitrogen atom, and the addition of methylhydrazine to the ethoxy group predominantly through the -nitrogen atom. Several derivatives of -alkyl(aryl)hydrazinomethyleneoxaloacetic esters have been obtained. A series of bis(methylamides) and several diamides of 1-alkyl(aryl)pyrazoledicarboxylic acids have been synthesized. Their structure has been determined on the basis of their UV spectra and their breakdown by hydrolysis to known acids. It has been found that in the alkylation of an ester of 3,4-pyrazoledicarboxylic acid with alkyl halides followed by amidation, two isomeric bis(methylamide)s are formed, apparently with the predominance of derivatives of 1-alkyl-3, 4-pyrazoledicarboxylic acids. It has been established that the bis(methylamide)s of 1-alkyl-3,4-pyrazoledicarboxylic and of 1-alkyl-4, 5-pyrazoledicarboxylic acids have characteristic UV spectra differing from one another. The bis(methylamide)s obtained are pharmacologically active substances.