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.

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

Manifestation of Vacancies in a Spectrum of Organic Molecular Crystal Lattice Vibrations

Using a method Raman of spectroscopy and considering a non-uniformity of allocation of vacancies in a monocrystal, it is shown that lines with the small intensity (caused by presence of vacancies) have a major intensity in the sample of a larger size than in the sample of a smaller size. Increase of an intensity of lines at vacancy concentration increase can reveal which lines are related to presence of vacancies in the sample. For a p-dichlorobenzene, it is lines of a small intensity in a spectrum of the lattice oscillations in the field of 70 cm^{-1}.Comment: 2 pages, PD

Arrangement of DOBAMBC molecules inside the capsule on change of the molecule's inclination on the border of the capsule investigated by the molecular dynamics method

The method of molecular dynamics is used to investigate the distribution of DOBAMBC molecules in a capsule with the fixed border layer. Change of an arrangement of molecules in smectic layers depending on an inclination of molecules on border is considered.Comment: 5 page