Dependence of the Compton to Rayleigh intensity ratio on the scatterer atomic number in the range of 4(Be) to 31(Ga)

Compton to Rayleigh scattering intensity ratios (I_C/I_R) have been measured using X-rays with energy 17.44 keV for single-component materials with atomic number Z from 4 (Be) to 31 (Ga) and binary compounds of stoichiometric composition. The measurements have been performed using two optical schemes: an energy-dispersive X-ray fluorescence scheme with a molybdenum secondary target and wavelength-dispersive X-ray fluorescence one. The processing of the spectra was carried out by fitting with Pearson VII functions. For single-component and binary standards, the experimental dependence of the scattering intensity ratio on the atomic number was found to be the same. This confirms the additivity of the contribution of different atoms to the scattering. The dependence has a complex shape but is well described by the theoretical relationship for I_C/I_R with correction on the difference between Compton and Rayleigh radiation absorption coefficients. Two ranges of atomic number values are defined, in which the effective atomic number Z_eff can be determined by the calibration method using this dependence: for Z from 4 to 7 with low error of ΔZ_eff =±0.15 and for Z_eff from 10 to 18 with low error of ΔZ_eff =±0.69. A change in the shape of the Compton peak and an overestimated value of the of the Compton and Rayleigh peak intensity ratio when passing from a single-component scatterer (Al or Si) to their oxides Al₂O₃ or SiO₂, respectively, have been revealed.     

Optical Properties and Radiation Stability of Sio2·nH2O Powders Modified by ZrO2 Nanoparticles

Russian Physics Journal -     

Efficiency of Two Approaches to Computing the Flow around an Airfoil with Flaps in the Case of Flow Separation

Computational Mathematics and Mathematical Physics - Model equations describing convective transport are used to analyze the approximation errors of an explicit numerical scheme and various...     

Low-Temperature Photolysis of Benzoyl Peroxide

Russian Journal of Physical Chemistry A - The photolysis of dry benzoyl peroxide (BP) at 77 K in the 480–236 nm range of wavelengths and an ethanol solution is studied via EPR. It is...     

Mass-spectrometric study of tellurium-film condensation and evaporation on sapphire

The processes of the condensation and evaporation of a tellurium film produced by a molecular beam of Te₂ on a sapphire surface are studied. It is experimentally shown that the desorption of tellurium from a surface upon growth under nonequilibrium conditions exceeds the equilibrium thermal desorption. If the beam intensity is less than the equilibrium value, then desorption is also lower than the equilibrium value. A model of this process with allowance for the transient states of tellurium in the adsorption layer is proposed. Within this model equilibrium and Langmuir beams are expressed in terms of the process parameters. The reflection coefficient of the beam is also a function of the process characteristics. The experimental data make it possible to estimate some of the basic parameters of the process, including the coverage and desorption rate in the adsorption layer. Taking these results into account is important for manufacturing perfect films not only of Te, but also of CdTe.     

Nanopowders of aluminum-magnesium spinel doped with europium(3+) ions: Synthesis by hydroxocarbonates coprecipitation and study of their physicochemical properties

Russian Journal of General Chemistry -     

Chiral acyclic diaminocarbene complexes of palladium(II) immobilized on a polymeric support as promising catalysts of the Suzuki reaction

Metal-promoted nucleophilic addition of primary amino group of a natural L-amino acid anchored on polystyrene support to coordinated isonitrile substrate has afforded preparation and simultaneous immobilization of chiral acyclic diaminocarbene complex of palladium(II). The obtained catalytic system is stable under conditions of the Suzuki reaction and demonstrates good catalytic activity in the reaction with a sterically hindered substrate.     

On parameter optimization upon the self-assembly of linear-chain carbon by the molecular dynamics method

The growth of linear-chain carbon on a substrate from a gas-vapor phase of carbon atoms by the molecular dynamics method is studied. The growth parameters are optimized to ensure the best conditions for obtaining linear-carbon chains of specified quality.