Nonthermal desorption of molecular ions of polyatomic molecules induced by uv laser radiation

The paper presents the results of studies into ion desorption from the surface of adenine and anthracene molecular crystals and anthracene molecules adsorbed on a metal as the surface is irradiated by an uv laser at λ=249, 308, and 337 nm. A sharp increase in molecular ion yield has been revealed with a decrease in radiation wavelength down to 249 nm. At this wavelength the effect of molecular ion desorption is observed at the radiation intensity of 20∶50 kW/cm² and pulse duration of 20 ns, it cannot be explained by thermal mechanisms. The initial velocity distribution of photoions is nonthermal by character, with maximum velocity of 2·10⁵ cm/s in case of adenine. The mechanisms responsible for the effect observed are discussed.     

Estimation of electron concentrations from oblique sounding data for a piecewise-one-dimensional model of the ionosphere

Translated from Aktual'nye Voprosy Prikladnoi Matematiki, pp. 28–31, 1989.     

Normal connection in the geometry of normalized submanifolds of affine space

A survey is given of results concerning the study of the structure of a normalized subraanifold of affine space with the help of a normal connection.Translated from Itogi Nauki i Tekhniki, Seriya Problemy Geometrii, Vol. 21, pp.93–107, 1989.     

Spectroscopical diagnostics of alpha particles in the TSP tokamak

Reported to the 5th All-Union Conference on High-Temperature Plasma Diagnostics (June 18–22, 1990, Minsk).     

Investigation of radical decay mechanisms in a glow-discharge plasma in carbon tetrafluoride

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 6, pp. 1004–1010, June, 1991.     

Interaction of CdSe/ZnS core-shell semiconductor nanocrystals in solid thin films

The optical properties of CdSe/ZnS semiconductor nanocrystals with the core-shell structure are studied upon visible-laser excitation in a wide range of flux densities. It is demonstrated that the dimensional quantization effect is preserved in the films with a limiting high concentration of nanocrystals. A strong bathochromic shift of the absorption and luminescence peaks relative to the peak positions in the corresponding spectra of nanocrystals in films with a relatively low concentration of nanocrystals and solutions is caused by a high concentration of nanocrystals and the dipole moment related to the asymmetry of the nanoparticles. The shift is varied from 35 to 50 nm depending on the film thickness. The luminescence spectra of the films remain unchanged upon an increase in the laser intensity to 1 × 10⁶ W/cm². The laser action on the nanoparticle films is studied at intensities (5 × 10⁶?1 × 10⁹ W/cm²) higher than the damage threshold.     

Preparation of activated carbons from cherry stones by activation with potassium hydroxide

Using cherry stones, the preparation of activated carbon has been undertaken in the present study by chemical activation with potassium hydroxide. A series of KOH-activated products was prepared by varying the carbonisation temperature in the 400-900 °C range. Such products were characterised texturally by gas adsorption (N₂, −196 °C), mercury porosimetry, and helium and mercury density measurements. FT-IR spectroscopy was also applied. The carbons prepared as a rule are microporous and macroporous solids. The degree of development of surface area and porosity increases with increasing carbonisation temperature. For the carbon heated at 900 °C the specific surface area (BET) is 1624 m² g⁻¹, the micropore volume is 0.67 cm³ g⁻¹, the mesopore volume is 0.28 cm³ g⁻¹, and the macropore volume is 1.84 cm³ g⁻¹.     

Evaluation of fluid-filled fractures during acoustic measurements on tube waves

The problem of reflection, transmission, and conversion of the tube wave on a fracture intersecting a borehole is investigated. We consider the case where an acoustic sonde is placed inside a borehole and the fracture separates two different elastic half-spaces and is filled with a porous material. Bibliography: 5 titles. __________ Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 324, 2005, pp. 121–128.