R. Alexandrescu

Time characteristics in laser diffusion of gaseous mixtures through capillaries

New experimental results are reported pointing to the temporal characteristics of gas mixture flows of resonant and nonresonant molecules through metallic capillary tubes under the action of low‐power cw CO2 laser radiation. While a selective laser action was always observed upon resonant molecules, a special category of nonresonant molecules is introduced whose transit through the capillary is influenced besides a pure thermal action by the vibrational energy transfer from the resonant molecules.

The effect of infrared laser radiation on the selectivity of gas-mixture flow through metal capillaries

Abstract The effect of infrared laser radiation on the flow of gas mixtures through metal capillaries is investigated. It is found that many characteristic features of the processes depend on the interaction of resonant molecules with the surface as well as on the input pressure at the capillary entrance. Special attention is paid to the establishment of conditions where there exists a selective effect of the laser radiation on the flow of the components of the gas mixture through the capillary.

Lase action on resonant molecular flows through capillaries

New experimental results are reported pointing to the possibility of a laser control of the resonant gases transit through capillaries in the Knudsen and intermediate regimes.

Infrared synthesis of SO3 by homogeneous gas-phase CO2 laser-driven reactions

Abstract By using a CO 2 laser operated at 10.6μm, a bimolecular reaction was induced in a binary SO 2 /O 2 gas mixture, with a sensitizer gas (SF 6 ) as photo-absorbing species. The infrared (IR) synthesis of SO 3 was performed in a flowing gas device equipped with a continuous trapping system of the reaction product. Vibrational energy transfer processes presumably should play a specific role in SO 2 excitation and reaction in the presence of SF 6 .

Resonant photoadsorption of uranyl ions in solution

Abstract Experimental evidence is given for the photoadsorption of uranyl ions in solutions, under the selective action of laser radiation. The effect was studied in two different systems involving uranyl solutions in contact with the surfaces of a ZnSe plate or a silicon wafer, respectively. Infrared spectrophotometrical methods as well as the measured value of the dielectric breakdown field showed in both cases an accumulation of resonant ions on the irradiated sites.

Surface alloying of silicon by laser aluminothermy

A new method is proposed for getting highly adherent Mo films on silicon wafers based upon laser‐induced aluminum reduction of metallic oxides.

Low-power-laser driven ultrafine silicon nitride production in a flowing system

Abstract Experimental results are reported on the efficient production of ultrafine silicone nitride powder appropriate for sintering of high-temperature ceramics by low-power IR (λ ≅s 10.6 μm) laser irradiation of gaseous mixtures in a flowing system.

Resonant photoadsorption of uranyl from an aqueous solution

Interaction of the 10.6 μm CO2 laser radiation with the ν3 vibrational mode of the UO2+ uranyl ion shifted the equilibrium in a heterophase system formed by a solid and a liquid solution in such a way as to increase the adsorption of uranyl.