Electron diffraction data on structural transformations in free clucters of argon

The paper presents the results of the experimental study of polarization bremsstrahlung profile halfwidth performed on free xenon clusters with various atom numbers. We used 0.7- and 0.3-keV electrons to excite mainly the core and the surface of the clusters, respectively. The halfwidth vs. atom number dependencies were found to be quite different for the 0.7- and 0.3-keV electrons. Analysis of the observed difference allowed us to conclude that the clusters with N = 2000-800...

Cathodoluminescence spectra of free xenon clusters produced by condensation of xenon-argon gas mixtures in supersonic jets expanding into vacuum were studied. By varying initial experimental parameters, including xenon concentration, we could obtain clusters with a xenon core (300-3500 atoms) covered by an argon outer shell as well as shell-free xenon clusters (about 1500 atoms). The cluster size and temperature (about 40 K for both cases) were measured electronographically. ...

In this work, we have investigated the interaction of a high-power Ar$^+$ laser beam, in a continuous multi-line regime, with Ag$^+$-doped glass samples. The samples were subjected to the irradiation after the ion-exchange step. As a result of the irradiation, a peak appears in the absorption spectrum; its evolution depends on both the exposure time and the laser beam power. Interaction of the beam with the clusters causes them break into smaller ones which has been confirmed...

An algorithm for determining crystal structures from diffraction data is described which does not rely on the usual Fourier-space formulations of atomicity. The new algorithm implements atomicity constraints in real-space, as well as intensity constraints in Fourier-space, by projections which restore each constraint with the minimal modification of the scattering density. To recover the true density, the two projections are combined into a single operation, the difference ma...

A generally accepted understanding of the anomalous properties of water will only emerge if it becomes possible to systematically characterize water in the deeply supercooled regime, from where the anomalies appear to emanate. This has largely remained elusive because water crystallizes rapidly between 160 K and 232 K. Here, we present an experimental approach to rapidly prepare deeply supercooled water at a well-defined temperature and probe it with electron diffraction befo...

In this article we report the release of a new program for batch processing and visualization of powder diffraction data. The program, which is free-of-charge for non-commercial use and can be obtained with its detailed documentation from our website www.scienceware.net, is currently in use by a number of researchers in University College London, University of Manchester, Utrecht University in the Netherland, European Synchrotron Radiation Facility (ESRF), and Diamond Light S...

The effect of intense X-ray laser interaction on argon clusters is studied theoretically with a mixed quantum/classical approach. In comparison to a single atom we find that ionization of the cluster is suppressed, which is in striking contrast to the observed behavior of rare-gas clusters in intense optical laser pulses. We have identified two effects responsible for this phenomenon: A high space charge of the cluster in combination with a small quiver amplitude and delocali...

Diffuse intensities in the electron diffraction patterns of concentrated face-centered cubic solid solutions have been widely attributed to chemical short-range order, although this connection has been recently questioned. This article explores the many non-ordering origins of commonly reported features using a combination of experimental electron microscopy and multislice diffraction simulations, which suggest that diffuse intensities largely represent thermal and static dis...

As in the available literature there are still misconceptions about powder diffraction phenomena observed for small nanocrystals ($D<10$ nm), we propose here a systematic and concise review of the involved issues that can be approached by atomistic simulations. Most of phenomenological tools of powder diffraction can be now verified constructing realistic atomistic models, following their thermodynamics and impact on the diffraction pattern. The models concern small cuts of t...

We have determined the ground-state energies of para-H$_2$ clusters at zero temperature using the diffusion Monte Carlo method. The liquid or solid character of each cluster is investigated by restricting the phase through the use of proper importance sampling. Our results show inhomogeneous crystallization of clusters, with alternating behavior between liquid and solid phases up to N=55. From there on, all clusters are solid. The ground-state energies in the range N=13--75 a...