Spatial properties of π−π\pi-\pi conjugated network in semicrystalline polymer thin films studied by intensity x-ray cross-correlation functions

We present results of x-ray study of spatial properties of $\pi-\pi$ conjugated networks in polymer thin films. We applied the x-ray cross-correlation analysis to x-ray scattering data from blends of poly(3-hexylthiophene) (P3HT) and gold nanoparticles. The Fourier spectra of the intensity cross-correlation functions for different films contain non-zero components of orders $n=2,4$ and $6$ measuring the degree of structural order in the system.Comment: 6 pages, 2 figures, Proceedings ICXOM22 Conference, 2-6 September 2013, Hamburg, German

Photoproduction of electron-positron pairs in bent single crystals

The process of photoproduction of electron-positron pairs in bent single crystals is considered in this paper. In particular, it is shown that the probability of the process for gamma-quanta with energies from 100 GeV on is significantly higher than the one in an amorphous medium. A possible scenario for the experimental validation of the process is discussed and the positive features of the photoproduction in bent crystals compared to straight ones are underlined from the point of view of possible applications.Comment: 13 pages, 6 figure

The use of incorrectly posed inverse problems and catastrophe theory in acoustoplasmic studies

If the discharge current into a plasma contains direct and variable components, the plasma develops wavelike acoustic instabilities and eventually becomes an acoustoplasmа. Such instabilities lead to bistability, multistability, and hysteresis phenomena of the current-voltage characteristics, causing abrupt changes in the state of the plasma medium. These changes can be imagined as phase transitions and described using catastrophe theory. In the present study, the experimental plasma data are approximated by the equations of catastrophes. After reducing the catastrophe equation to canonical form, the points of possible phase transitions are determined. The phase transition coordinates are then converted to coordinates in the experimental system by inverse trans-formations. In this way, we determine the points of possible phase transitions in a real experiment. Finally, the parameter changes in an acoustoplasma discharge are obtained by solving incorrectly posed inverse problems. The inverse problem of the experi-mental data is solved at each current time. Within the neighborhoods of singular points, the incorrectly posed inverse problems are solved by the theory of catastrophes. The proposed methods are applicable to various fields of science and technology.Если ток разряда в плазме содержит прямые и переменные компоненты, плазма развивает волнообразную акустическую нестабильность и в результате становится акустоплазмой. Такие неустойчивости приводят к явлениям бистабильности, мультистабильности и гистерезиса вольт-амперных характеристик, вызывая резкие изменения состояния плазменной среды. Эти изменения могут быть представлены как фазовые переходы. В настоящей работе экспериментальные данные плазмы аппроксимируются уравнениями катастроф. После приведения в соответствие уравнения катастрофы к канонической форме соответствуют точке фазовых переходов. Координаты фазового перехода преобразуются в координаты экспериментальной системы с помощью преобразований.В этом случае мы определяем точки Наконец, изменения параметров в акустической плазме получены с помощью решений. Обратная задача экспериментальных данных решается в каждом текущем моменте времени. В окрестностях особых точек неверно поставлены обратные задачи решаются теорией катастрофы. Предлагаемые методы применимы к различным областям науки и техники

Local structure of semicrystalline P3HT films probed by nanofocused coherent x-rays

We present results of an x-ray study of structural properties of semicrystalline polymer films using nanofocused x-ray beam. We applied the x-ray cross-correlation analysis (XCCA) to scattering data from blends of poly(3-hexylthiophene) (P3HT) embedded with gold nanoparticles (AuNPs). Spatially resolved maps of orientational distribution of crystalline domains allow us to distinguish sample regions of predominant face-on morphology,with a continuous transition to edge-on morphology. The average size of crystalline domains was determined to be of the order of 10 nm. As compared to pristine P3HT film, the P3HT/AuNPs blend is characterized by substantial ordering of crystalline domains, which can be induced by Au nanoparticles. The inhomogeneous structure of the polymer film is clearly visualized on the spatially resolved nanoscale 2D maps obtained using XCCA. Our results suggest that the observed changes of the polymer matrix within crystalline regions can be attributed to nanoconfinement in the presence of gold nanoparticles.Comment: 10 pages, 6 figures, 53 reference

Local structure of semicrystalline P3HT films probed by nanofocused coherent X-rays

The hidden structural properties of semicrystalline polymer films are revealed by nanofocused X-ray scattering studies. X-ray cross-correlation analysis (XCCA) is employed to diffraction patterns from blends of poly(3-hexylthiophene) (P3HT) with gold nanoparticles (AuNPs). Spatially resolved maps of orientational distribution of crystalline domains allow us to distinguish sample regions of predominant face-on morphology, with a continuous transition to edge-on morphology. The average size of crystalline domains was determined to be of the order of 10 nm. As compared to pristine P3HT film, the P3HT/AuNPs blend is characterized by substantial ordering of crystalline domains, which can be induced by Au nanoparticles. The inhomogeneous structure of the polymer film is clearly visualized on the spatially resolved nanoscale 2D maps obtained using XCCA. Our results suggest that the observed changes of the polymer matrix within crystalline regions can be attributed to nanoconfinement in the presence of gold nanoparticles. This journal i

The digitized first Byurakan survey – DFBS

Context.The First Byurakan Survey (FBS), also known as the Markarian Survey, is the largest low resolution spectroscopic survey of the sky and led to the discovery of 1500 UV-excess (UVX) galaxies and starburst galaxies. The FBS plates have also been used to search for UVX stellar objects, late-type stars, and for the identification of unusual infrared sources. Aims.The Digitized First Byurakan Survey (DFBS) provides the astronomical community with a digitized version of the FBS images and with the extracted spectra for the objects present in the plates. Methods.Nearly 2000 plates have been scanned and stored and programs were developed to compute the astrometric solution, extract the spectra, and apply wavelength and photometric calibration for the objects present in the plates. Results.The DFBS database and catalog of objects has been assembled. The DFBS database contains data for 20 000 000 objects present in the survey and provides tools for accessing the DFBS. Conclusions.New scientific projects as well as existing surveys will benefit by the digitized images and the ready-to-use extracted spectra which will allow an efficient computer-based analysis of the dataset