The influence of excitation radiation parameters on photosensitized generation of singlet oxygen in water

Photosensitized generation of singlet oxygen with the aid of Radahlorin® photosensitizer has been investigated. The dependences of the intensity of singlet oxygen phosphorescence and photosensitizer fluorescence on the excitation radiation wavelength in the range of 350–440 nm and on the irradiation dose have been obtained. The dependence of the ratio of the sensitizer fluorescence intensity at about 670 nm to the singlet oxygen phosphorescence intensity at a wavelength of 1270 nm on the excitation radiation wavelength is found to be nonmonotonic and have a minimum near the center of the absorption band on its red wing. The results obtained can be used to monitor the singlet oxygen concentration in solutions.     

Laser Photoacoustic Detection of Residual Stresses in Metal Plates with a Hole

Doklady Physics - The character of variation in a photoacoustic signal around a hole in duralumin samples is studied. The experimental results are compared with the solution of the classical...     

Morphology of polycrystalline cassiterite films

Polycrystalline cassiterite films have been grown by the hydropyrolytic method from a 10(H₂O) + 5(SnCl₂ · 2H₂O) solution (in weight fractions) on corundum substrates. The crystallization regularities are considered and a comparative analysis of the properties of natural and artificial cassiterite crystals is performed. The surface morphology is investigated and the size of crystalline grains is determined by scanning electron microscopy. X-ray microprobe analysis showed that all films contain tin and oxygen atoms in a ratio corresponding (within the experimental error) to the chemical formula of tin dioxide. It is established that the surface morphology of cassiterite films is characterized by both single crystallites and aggregates of two or more crystals typical of twins. It is suggest that doping can efficiently be used to control the concentration of twins and the stability of their formation.     

Test of many-electron QED effects in the hyperfine splitting of heavy high-Z ions

A rigorous evaluation of the two-photon exchange corrections to the hyperfine structure in lithiumlike heavy ions is presented. As a result, the theoretical accuracy of the specific difference between the hyperfine splitting values of H- and Li-like Bi ions is significantly improved. This opens a possibility for the stringent test of the many-electron QED effects on a few percent level in the strongest electromagnetic field presently available in experiments.     

Temporal dissipative structures in cyclically deformed metallic alloys

cyclically deformed metallic alloys. The model employs quasi-chemical reactions of multiplication, annihilation and positive feedback among the populations of mobile, immobile, and Cottrell-type dislocations [1]. Three major types of loading have been simulated, namely, pure sinusoidal, “creep fatigue”, and ramp loading. Computer movies of the temporal evolution of stress serrations and dislocation densities have been produced as an aide for analysis and illustration. It has been demonstrated that the model successfully reproduces strain bursts and stress serrations in fatigued metallic alloys in terms of the underlying dislocations mechanisms, thus establishing the fundamental connection between micro- and macromechanics of cyclic deformation. Received: 20 June 1996/Accepted: 6 October 1996     

Saturated Vapor Pressure over the Melts of the NaNO2-NaNO3 System

The partial pressures of sodium nitrite and sodium nitrate over the system NaNO₂-NaNO₃ were determined at 798, 823, and 848°C. For sodium nitrate, A and B coefficients of the Clausius-Clapeyron equation, partial molar heats of vaporization, activities, and activity coefficients were calculated as functions of composition.     

g factor of the [(1s)2(2s)22p]2P3/2 state of middle-Z boronlike ions

Theoretical g-factor calculations for the first excited ²P_3/2 state of boronlike ions in the range Z=10–20 are presented and compared with the previously published values. The first-order interelectronic-interaction contribution is evaluated within the rigorous quantum electrodynamics (QED) approach in the effective screening potential. The second-order contribution is considered within the Breit approximation. The QED and nuclear recoil corrections are also taken into account.     

Two-dimensional nonlinear electromagnetic waves in a carbon nanotube array

Physics of the Solid State - The interaction of electromagnetic waves with carbon nanotubes has been investigated theoretically. The dynamics of nonlinear electromagnetic waves is considered in...