Andrei Petukhov | Utrecht University (original) (raw)

Papers by Andrei Petukhov

IUCrJ

An application of angular X-ray cross-correlation analysis (AXCCA) to the scattered intensity dis... more An application of angular X-ray cross-correlation analysis (AXCCA) to the scattered intensity distribution measured in 3D reciprocal space from a single-crystalline sample is proposed in this work. Contrary to the conventional application of AXCCA, when averaging over many 2D diffraction patterns collected from different randomly oriented samples is required, the proposed approach provides an insight into the structure of a single specimen. This is particularly useful in studies of defect-rich samples that are unlikely to have the same structure. The application of the method is shown on an example of a qualitative structure determination of a colloidal crystal from simulated as well as experimentally measured 3D scattered intensity distributions.

$Research paper thumbnail of Diffraction based Hanbury Brown and Twiss interferometry at a hard x-ray free-electron laser$

Scientific Reports, 2018

X-ray free-electron lasers (XFELs) provide extremely bright and highly spatially coherent x-ray r... more X-ray free-electron lasers (XFELs) provide extremely bright and highly spatially coherent x-ray radiation with femtosecond pulse duration. Currently, they are widely used in biology and material science. Knowledge of the XFEL statistical properties during an experiment may be vitally important for the accurate interpretation of the results. Here, for the first time, we demonstrate Hanbury Brown and Twiss (HBT) interferometry performed in diffraction mode at an XFEL source. It allowed us to determine the XFEL statistical properties directly from the Bragg peaks originating from colloidal crystals. This approach is different from the traditional one when HBT interferometry is performed in the direct beam without a sample. Our analysis has demonstrated nearly full (80%) global spatial coherence of the XFEL pulses and an average pulse duration on the order of ten femtoseconds for the monochromatized beam, which is significantly shorter than expected from the electron bunch measurements.

Soft matter, Jan 10, 2018

The structural rearrangement of polystyrene colloidal crystals under dry sintering conditions has... more The structural rearrangement of polystyrene colloidal crystals under dry sintering conditions has been revealed by in situ grazing incidence X-ray scattering. The measured diffraction patterns were analysed using distorted wave Born approximation (DWBA) theory and the structural parameters of the as-grown colloidal crystals of three different particle sizes were determined for the in-plane and out-of-plane directions in a film. By analysing the temperature evolution of the diffraction peak positions, integrated intensities, and widths, the detailed scenario of the structural rearrangement of crystalline domains at the nanoscale has been revealed, including thermal expansion, particle shape transformation and crystal amorphisation. Based on DWBA analysis, we demonstrate that in the process of dry sintering, the shape of colloidal particles in a crystal transforms from a sphere to a polyhedron. Our results deepen the understanding of the thermal annealing of polymer colloidal crystals...

Soft matter, Jan 26, 2018

For magnetite spherical nanoparticles, the orientation of the dipole moment in the crystal does n... more For magnetite spherical nanoparticles, the orientation of the dipole moment in the crystal does not affect the morphology of either zero field or field induced structures. For non-spherical particles however, an interplay between particle shape and direction of the magnetic moment can give rise to unusual behaviors, in particular when the moment is not aligned along a particle symmetry axis. Here we disclose for the first time the unique magnetic properties of hematite cubic particles and show the exact orientation of the cubes' dipole moment. Using a combination of experiments and computer simulations, we show that dipolar hematite cubes self-organize into dipolar chains with morphologies remarkably different from those of spheres, and demonstrate that the emergence of these structures is driven by competing anisotropic interactions caused by the particles' shape anisotropy and their fixed dipole moment. Furthermore, we have analytically identified a specific interplay betw...

Journal of Chemical Physics, Oct 28, 2008

$Research paper thumbnail of Small-angle X-ray diffraction investigation of twinned opal-like structures$

Physics of the Solid State, 2012

Journal of Physics: Condensed Matter, 2012

Using microradian x-ray scattering and polarized light microscopy the rich liquid crystalline pha... more Using microradian x-ray scattering and polarized light microscopy the rich liquid crystalline phase behaviour of a polydisperse system of chromium-modified goethite particles has been studied for five years. We observe that the particles stay highly mobile over years and the rich phase behaviour keeps developing in novel and even surprising ways. While in many other colloidal systems particle size polydispersity suppresses the formation of ordered phases, goethite particles form multiple coexisting ordered phases. The particle polydispersity problem is then solved by particle exchange between coexisting phases. One usually expects that a less ordered phase (e.g., nematic) is formed first while crystallization of the smectic and columnar crystals might take a longer time. For goethite particles we find the opposite, i.e. the nematic phase grows over years at the expense of a better ordered smectic phase. Moreover, SAXS patterns revealed peak splitting for both the smectic and the columnar phase, meaning that the system displays fractionated crystallization. We further discovered that the centred rectangular columnar phase spontaneously forms out of the simple rectangular columnar phase. The reverse transition is observed as well. We explain the ease of these martensitic transitions by showing how slight rotation and translation of the particles triggers the transition.

The Journal of Physical Chemistry Letters, 2010

We found, using polarization microscopy and small-angle X-ray scattering, that for goethite, a lo... more We found, using polarization microscopy and small-angle X-ray scattering, that for goethite, a low polydispersity suffices to form two separate nematic phases, while previous theory showed that this is only possible for mixtures of particles with extremely different lengths or diameters. Applying a critical magnetic field, which induces some of the goethite nanorods to rotate, leads to sufficient excluded volume between the particles to cause macroscopic phase separation between two orthogonal nematic phases. The larger the polydispersity of the system, the broader the range of field strengths where nematic−nematic phase separation occurs. This is a new phase separation mechanism which is expected to lead to interesting interfacial phenomena.

Physical Review B, Oct 13, 2014

Journal of Applied Crystallography, Sep 20, 2019

Journal of Physical Chemistry C, Dec 5, 2017

Current Opinion in Colloid & Interface Science, 2015

Small-angle X-ray scattering (SAXS) is an indispensable tool in structural investigations of self... more Small-angle X-ray scattering (SAXS) is an indispensable tool in structural investigations of self-assembled colloidal crystals and colloidal liquid crystals. This paper reviews recent studies of the particle shape effects on the crystal structure as revealed by SAXS. Rod-like, plate-like, biaxial board-like as well as cubic-like shapes are discussed. Since relatively large, (sub)micron particles are often used in these studies, we describe the principles of the microradian X-ray diffraction technique that allows detailed characterisation of the periodic order including the determination of the intrinsic width of the Bragg peaks.

Nature communications, Jun 3, 2016

Despite the availability of elaborate varieties of nanoparticles, their assembly into regular sup... more Despite the availability of elaborate varieties of nanoparticles, their assembly into regular superstructures and photonic materials remains challenging. Here we show how flexible films of stacked polymer nanoparticles can be directly assembled in a roll-to-roll process using a bending-induced oscillatory shear technique. For sub-micron spherical nanoparticles, this gives elastomeric photonic crystals termed polymer opals showing extremely strong tunable structural colour. With oscillatory strain amplitudes of 300%, crystallization initiates at the wall and develops quickly across the bulk within only five oscillations. The resulting structure of random hexagonal close-packed layers is improved by shearing bidirectionally, alternating between two in-plane directions. Our theoretical framework indicates how the reduction in shear viscosity with increasing order of each layer accounts for these results, even when diffusion is totally absent. This general principle of shear ordering in...

This dataset contains all raw 2D small-angle x-ray scattering (SAXS) images for <i>in-situ ... more This dataset contains all raw 2D small-angle x-ray scattering (SAXS) images for <i>in-situ </i>silica superball crystallization. Colloidal crystallization was obtained under spherical confinement via a drying droplet for all experiments. The corresponding 2D SAXS calibration file is also included.

$Research paper thumbnail of Coherent x-ray diffraction imaging of a single colloidal crystal grain$

1Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, D-22607 Hamburg, Germany 2A. V. Shubnikov I... more 1Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, D-22607 Hamburg, Germany 2A. V. Shubnikov Institute of Crystallography RAS, Leninskii pr. 59, 119333 Moscow, Russia 3Debye Institute, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands 4NRC ”Kurchatov Institute”, pl. Akademika Kurchatova, Moscow, 123182, Russia 5National Research Nuclear University MEPhI, Kashirskoye shosse 31, Moscow, 115409, Russia 6Institute for X-Ray Physics, Friedrich-Hund-Platz 1, 37077 Gottingen, Germany

$Research paper thumbnail of In situ X-ray diffraction studies of structure evolution in colloidal crystals in the vicinity of melting transition$