[en] The methods of ESR, optical and mass-spectroscopy have been used to study the formation and decay of active intermediates, radiation and photoradiation gas evolution in a series of combined polymeric materials. The investigated samples were films of polyimide (PI), one- or two-side coated PI-fluoroplast, poly(ethylene terephthalate) (PET), PET coated with polyacryl on both sides, etc. Different coatings and polymeric substrates have been established to produce a mutual effect on the radiation- and photo-induced transformations of the combined polymers at the stage of radical formation and gas evolution. Thus, γ-irradiation of PI-fluoroplast films at 300 K intensifies the radiation-chemical processes in the fluorinated coatings, namely, the radiation-chemical yield of macroradicals in the coatings is several times higher than that in fluoro-containing polymers. In the PET film coated with polyacryl the yield of macroradicals related to polyacrylic acid is significantly lower than the value generally cited in the publications. A mutual effect of the coatings and substrates on the radiation and photoradiation-induced gas evolution is even more noticeable. Thus, a gas mixture of the PI-fluoroplast film contains lower amounts of carbon oxide and fluorinated products and no hydrogen at all. The interphase processes, distortion of the boundary layer structure, electronic equilibrium, mutual effect of the evolved gases, etc. can account for the reasons of such non-additivity

[en] History of the discovery by Laue of X-ray diffraction is presented. It is shown that Laue's discovery permitted to develop method of X-ray diffraction analysis elucidating the earlier unknown world of atomic structure of substance. Due to this method at present atomic structure of many simple and complex compounds, metals, alloys and objects of natural origin is known. Study of X-ray diffuse scattering in reciprocal space and of regions around reciprocal lattice points gives a technique of studying crystal dynamics (phonon spectra), of using purely X-ray diffraction method for measuring elastic constants of crystals and their Debye temperature

[en] Solution of Nasarov-Gurov equation for mutual diffusion accounting nonequilibrium vacancies for their initial distribution special mode is obtained. Evolution of distribution curves of excess vacancies and A type atomic concentration deviation from the equilibrium value for different parameters is shown

[en] This paper points out the potential advantages of electron microscopy in the study of crystallization; this technique is so far very much in the shadow of the classical methods. The high resolution of the microscope makes it possible to decrease sample volumes by many orders of magnitude, which increases the probability of achieving larger supercooling. The authors present certain concepts from the theory of crystallization in order to analyze the experimental results; these include the fundamentals of the crystal nucleation theory, and the crystallization and melting of small particles. THe highly dispersed structure of ultra-thin metal films makes them suitable for studying melting and crystallization of small particles. The authors describe the growth, melting, and crystallization of indium islands observed in ultra-high vacuum and recorded by a microdiffraction technique. These and other experimental techniques are described. Results are given of mercury and tin droplet crystallization

[en] By X-ray analysis and electron diffraction microscopy it is established that Cu₃₅Zr₆₅ amorphous alloy is subjected to natural ageing. Partial crystallization of CuZr₂ phase occurs in the alloy when allowing it at room temperature during three years. Microheterogeneity of short-range order both topological and composite is shown to be observed in the amorphous phase after partial crystallization

No abstract available

[en] Using the method of EPR and optical spectroscopy investigation of the nature of color centres of polymethylmethacrylate (PMMA), appearing under the effect of ß-irradiation, has been carried out. The irradiation is conducted in the air at 77 and 300 K with doses from 1 to 200 kGy. It has been established that terminal alkyl macroradicals approximately CH²-C(CH³)(COOCH³) are responsible for PMMA colouring. Absorption is conditioned by ''+orbidden'' transition σ → p with lambdasub(max)=425 nm and extinction coefficient epsilon=(4+-1)x10₃ lxmol^-₁ m^-₁. Optical absorption spectra of ß-irradiated PMMA (visible region of spectrum) as well as curves of terminal macroradical and color centre accumulation at 373 K are presented

[en] The EPR method was used to study the formation, stabilization, and post-irradiation breakdown of macroradicals during irradiation at 0.015 to 7.7 Gy/sec of polymethyl methacrylate in a vacuum at room temperature. The macroradical concentration has a maximum whose position depends on the dose rate. The radiochemical yield of macroradicals is G(R) = 3.5. Observed changes in the EPR spectra were caused by a decrease in the concentration of terminal alkyls and an accumulation of allyl and polyenoic macroradicals. The experimental results are explained by the enhancement of secondary reactions between the macroradicals and molecules of the products from decomposition of the polymer chains

[en] Short note. 1 ref

[en] The sorption rate of dimethylformamide (DMF) onto thin polyethylene terephthalate (PETP) films is reduced after they have been irradiated by 1 MeV¹²⁹₅₄Xe ions or by ⁶⁰Co γ rays. It is suggested that defects in the PETP matrix structure interact with DMF molecules and lower their diffusion rate. When the heavy ions impact the polymer, they generate shock waves, which interact with the polymer and create defects at a higher rate [per unit of radiative energy] for ion irradiation than for γ irradiation