Superconducting state in Fe-based materials and spin-fluctuation theory of pairing

Short review of the spin-fluctuation theory of superconductive pairing in iron-based pnictides and chalcogenides.Comment: English translation of publication in Russian: Uspekhi Fizicheskikh Nauk 184 (8), 882-888 (2014), DOI: 10.3367/UFNr.0184.201408h.088

Observation of the Accelerated Diffusion in Nanoparticles of Paradibromobenzene /Paradihlorbenzene Solid Solution

P-dibromobenzene nanoparticles in a case of paradihlorbenzol molecules have been synthesized. Raman spectrums of these nanoparticles are measured. At diffusion of molecules of paradihlorbenzol in a pdibromobenzene nanoparticle solid solution formed. Modifications in structure of nanoparticles at diffusion are reflected in Raman spectrums. Unlike a solid solution single crystal, in nanoparticles the accelerated diffusion, $D = 1.3 \pm 0.02 10^{-11} cm^2/s$, is observed at room temperature. Calculations show that the accelerated diffusion is caused by magnification of parametres of a lattice at reduction of sizes of nanoparticles.Comment: 3 page

Study Influence of Doping on Temperature Dependence of Diffusion Rate in Organic Molecular Crystals

It is experimentally shown, that doping an organic molecular crystal reduces diffusion rate of impurity. Also reduces its influence on a modification of temperature. Examinations are lead on a crystal paradibromobenzene doping by paradiclorobenzene. Diffusing impurity was parabromochlorobenzene.Comment: 3 page

Examination of the Allocations of Building Molecules in the Single Crystal of the Para-Dichlorbenzol with the P-Dibromobenzene Solid Solution by the Method of the Raman Effect of Light Depending on Requirements of Selection

Allocation of molecules of para-dichlorbenzol in equimolar single crystals of para-dichlorbenzol with p-dibromobenzene solid solutions grown by the Bridgmen's method is studied. It is shown, that the mutual concentration of builders longwise an exemplar depends on requirements of selection. Probably as a uniform modification of concentration of builders along an exemplar, and a wavy modification of concentration. Critical speed at a modification of character of allocation made 15.0 $\cdot$10-6 cm/s at a lapse rate of temperature dT/dl=7.7 grad/cm.Comment: 2 page

Determination of the paradihlorobenzene and paradibromobenzene solid solutions nanoparticles structure via Raman spectra

We measured the small frequencies Raman spectrum of the paradihlorobenzene and paradihlorobenzene solid solution nanoparticles with the size about 100 nanometers. Values of frequencies of lines decrease. The size of nanoparticles was determined by the electronic microscope. Calculations of nanoparticles structure were done using the method of molecular dynamics and histograms of nanoparticles spectra were calculated via the Dyne's method. The result is that the Raman spectrum is the sum of spectra from the central part of the nanoparticle and superficial structures with smaller concentration of paradihlorobenzene.Comment: 4 page

Influence of Vacancies on the Nanoparticle Pulsation

Computer modeling of the one-dimensional and three-dimensional nanoparticles with Van-der-Waals interaction was performed. The arrangement of atoms was defined on the grounds of an energy minimum. The calculations have shown that in the presence of vacancies in a nanoparticle and the account of a relaxation and oscillations the nanoparticle will pulse. This pulsation on distance between atoms of a nanoparticle is observed in both one-dimensional and a three-dimensional cases.Comment: 2 page

The Reasons of Line Broadening of Lattice Oscillations in Spectrum Small Frequencies of P-Chloronitrobenzene

Raman spectroscopies are carried out by the Method polarizable examinations of the lattice oscillations of p-chloronitrobenzene at temperature 293 K. The led matching of spectrums of p-chloronitrobenzene with p-bromochlorobenzene and p-dibromobenzene has shown that the significant line broadening in p-chloronitrobenzene is caused not only clutter in allocation of molecules concerning parasubstitution benzol. It is necessary to consider also and clutter in rotational displacements of the nitro of group concerning a plane of a molecule. Calculations of frequency spectra were led on a method the Dyne.Comment: 4 pages, PDF PACS: 78.30. E; 61.72. J; 61.66. H; 78.30.

Calculation of Spectra of the Lattice and Surface Vibrations of Organic Nano-Crystals

Calculations of frequencies of the lattice and surface oscillations of organic nano-crystals are carried out. As the sample the para-dichlorobenzol has been chosen. Change of spectra of oscillations from the sizes of nano-particles is found. It is shown that with the reduction of the sizes of nano-particles a spectrum of the surface oscillations prevailing. Calculations have shown that for the correct interpretation of the observational spectra it is necessary to consider orientation disorder of the surface molecules and presence of vacancies in nano-particle volume.Comment: 2 pages, 4 figure

Determination of Vacancies Allocation in a Monocrystal of a P-Dichlorobenzene Using a Method of the Raman Spectroscopy

The method of Raman scattering is used to investigate the cross edge of a p-dichlorobenzene monocrystal, which was grown up by a Bridgmen method. Comparison of intensities of additional lines of a spectrum of the lattice oscillations of certain parts of an edge of a monocrystal with density of these fields has allowed to relate some lines to presence of vacancies in structure.Comment: 2 pages, PD

Raman Spectroscopy of the Eutectic in the Mixed Crystal of the Para-Dibromobenzene with the Para-Chloronitrobenzene

The mixed crystal of a para-dibromobenzene with a para-chloronitrobenzene is investigated at concentration of components from 0% up to 60% of a para-chloronitrobenzene by the method of Low-Frequency Raman spectroscopy. It is shown, that in range of concentrations from 25% up to 50% of a para-chloronitrobenzene the spectrum of the mixed crystal would consist of the sum of spectrums a and b phases which relation of intensities depends on concentration of components. It is also found, that the single crystal in this range has rod frame.Comment: 3 pages, 2 figur