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A. V. Petukhov

Publications and source records attributed to A. V. Petukhov.

7 recordsLinked to original sources
arXiv2017

Diffraction based Hanbury Brown and Twiss interferometry performed at a hard x-ray free-electron laser

We demonstrate experimentally Hanbury Brown and Twiss (HBT) interferometry at a hard X-ray Free Electron Laser (XFEL) on a sample diffraction patterns. This is different from the traditional approach when HBT interferometry requires direct beam measurements in absence of the sample. HBT analysis was carried out on the Bragg peaks from the colloidal crystals measured at Linac Coherent Light Source (LCLS). We observed high degree (80%) spatial coherence of the full beam and the pulse duration of the monochromatized beam on the order of 11 fs that is significantly shorter than expected from the electron bunch measurements.

physics.optics↗
arXiv2016

Revealing three-dimensional structure of individual colloidal crystal grain by coherent x-ray diffractive imaging

We present results of a coherent x-ray diffractive imaging experiment performed on a single colloidal crystal grain. The full three-dimensional (3D) reciprocal space map measured by an azimuthal rotational scan contained several orders of Bragg reflections together with the coherent interference signal between them. Applying the iterative phase retrieval approach, the 3D structure of the crystal grain was reconstructed and positions of individual colloidal particles were resolved. As a result, an exact stacking sequence of hexagonal close-packed layers including planar and linear defects were identified.

cond-mat.mtrl-sci↗
arXiv2012

Dynamics of colloidal crystals studied by pump-probe experiments at FLASH

We present a time-resolved infrared (IR) pump and extreme-ultraviolet (XUV) probe diffraction experiment to investigate ultrafast structural dynamics in colloidal crystals with picosecond resolution. The experiment was performed at the FLASH facility at DESY with a fundamental wavelength of 8 nm. In our experiment, the temporal changes of Bragg peaks were analyzed and their frequency components were calculated using Fourier analysis. Periodic modulations in the colloidal crystal were localized at a frequency of about 4-5 GHz. Based on the Lamb theory, theoretical calculations of vibrations of the isotropic elastic polystyrene spheres of 400 nm in size reveal a 5.07 GHz eigenfrequency of the ground (breathing) mode.

cond-mat.mtrl-sci↗
arXiv2010

The number of master integrals is finite

For a fixed Feynman graph one can consider Feynman integrals with all possible powers of propagators and try to reduce them, by linear relations, to a finite subset of integrals, the so-called master integrals. Up to now, there are numerous examples of reduction procedures resulting in a finite number of master integrals for various families of Feynman integrals. However, up to now it was just an empirical fact that the reduction procedure results in a finite number of irreducible integrals. It this paper we prove that the number of master integrals is always finite.

hep-th↗
arXiv2000

(Meta-)stable reconstructions of the diamond(111) surface: interplay between diamond- and graphite-like bonding

Off-lattice Grand Canonical Monte Carlo simulations of the clean diamond (111) surface, based on the effective many-body Brenner potential, yield the $(2\times1)$ Pandey reconstruction in agreement with \emph{ab-initio} calculations and predict the existence of new meta-stable states, very near in energy, with all surface atoms in three-fold graphite-like bonding. We believe that the long-standing debate on the structural and electronic properties of this surface could be solved by considering this type of carbon-specific configurations.

cond-mat.mtrl-sci↗
arXiv2000

Reconstructions of diamond (100) and (111) surfaces: Accuracy of the Brenner potential

We present a detailed comparison of the structural predictions of the effective many-body Brenner potential with those of ab-initio studies for known reconstructions of diamond (100) and (111) surfaces. These results suggest high reliability of the Brenner potential for dealing with carbon-based structures where different types of bonding are present at the same time.

cond-mat.mtrl-sci↗