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We have investigated the formation of microparticles-based Coulomb crystals in a linear vertical quadrupole Paul trap with a single end-cap electrode. For the first time, we have described the effect of gravity on Coulomb crystals formation. We have observed a new type of stable Coulomb crystals configuration that we referred to as "Christmas tree-like Coulomb crystals". We have provided numerical simulation and experimental research of the "Christmas tree-like Coulomb crystals" and discussed these structures in the perspective of Science and Art performance.

We use the picosecond acoustic pump-probe technique to study the elastic properties of monodispersemesoporous silica spheres filled with nickel and deposited in the form of opal-like films on silica substrates. The picosecond pump-probe optical transmission signal shows harmonic oscillations corresponding to the lower energy radial Lamb mode in the vibrational spectrum of the spheres. These oscillations, with a frequency of several gigahertz last for several nanoseconds in the spheres with diameter 1050 nm, showing high homogeneity of the sphere parameters. By analysis of the oscillation spectrum of films with different sphere diameter and nickel content we obtain the elastic moduli of the mesoporous silica spheres., Comment: 7 pages, 3 figures, 1 table

The results of spectroscopic studies of the diffraction anomalies (the so-called resonant Wood anomalies) in spatially-periodic hybrid structures based on halcogenide (GST225)-coated opal films of various thickness are presented. A theoretical analysis of spectral-angular dependencies of the Wood anomalies has been made by means of a phenomenological approach using the concept of the effective refractive index of waveguiding surface layer., Comment: 6 pages, 6 figures

Neutron diffraction studies of antiferromagnetic CoO confined to a vycor type porous glass demonstrate a continuous magnetic phase transition with a decreased N\'eel temperature and reduced magnetic moment as compared with the bulk., Comment: 3 pages, 2 figures

Electron spin resonance (ESR) experiments were performed with antiferromagnetic MnO confined within a porous vycor-type glass and within MCM-type channel matrices. A signal from confined MnO shows two components from crystallized and amorphous MnO and depends on the pore topology. Crystallized MnO within a porous glass shows a behavior having many similarities to the bulk. In contrast with the bulk the strong ESR signal due to disordered "surface" spins is observed below the magnetic transition. With the decrease of channel diameter the fraction of amorphous MnO increases while the amount of crystallized MnO decreases. The mutual influence of amorphous and crystalline MnO is observed in the matrices with a larger channel diameter. In the matrices with a smaller channel diameter the ESR signal mainly originates from amorphous MnO and its behavior is typical for the highly disordered magnetic system., Comment: 7 pages pdf file, 5 figures

Neutron diffraction studies of antiferromagnetic MnO confined to MCM-41 type matrices with channel diameters 24-87 A demonstrate a continuous magnetic phase transition in contrast to a discontinuous first order transition in the bulk. The character of the magnetic transition transforms with decreasing channel diameter, showing the decreasing critical exponent and transition temperature, however the latter turns out to be above the N\'eel temperature for the bulk. This enhancement is explained within the framework of Landau theory taking into consideration the ternary interaction of the magnetic and associated structural order parameters., Comment: 6 pages pdf file, including 4 figures, uses revtex4.cls

X-ray diffraction experiments were performed on MnO confined in mesoporous silica SBA-15 and MCM-41 matrices with different channel diameters. The measured patterns were analyzed by profile analysis and compared to numerical simulations of the diffraction from confined nanoparticles. From the lineshape and the specific shift of the diffraction reflections it was shown that the embedded objects form ribbon-like structures in the SBA-15 matrices with channels diameters of 47-87 {\AA}, and nanowire-like structures in the MCM-41 matrices with channels diameters of 24-35 {\AA}. In the latter case the confined nanoparticles appear to be narrower than the channel diameters. The physical reasons for the two different shapes of the confined nanoparticles are discussed., Comment: 8 pages, including 9 postscript figures, uses revtex4.cls