Показано, что ориентация поверхностного рельефа в виде одномерных решеток с периодом 1.20 ± 0.02 µm, формируемого при обработке пленок аморфного гидрогенизированного кремния фемтосекундными лазерными импульсами (1.25 µm) с плотностью энергии 0.15 J/cm 2 , определяется направлением вектора поляризации использованного излучения и совокупной дозой экспозиции.В облученных областях пленок зарегистрировано присутствие нанокристаллической фазы кремния, объемная доля которой (в зависимости от условий обработки) составляет от 15 до 67% согласно результатам анализа спектров комбинационного рассеяния света.Наблюдаемые процессы микро-и наноструктурирования обусловлены соответственно возбуждением поверхностных плазмон-поляритонов и нанокристаллизацией в приповерхностной области в поле мощных фемтосекундных лазерных импульсов.Кроме того, обнаружено формирование полиморфных модификаций кремния Si-III и Si-XII при фемтосекундной лазерной обработке с числом импульсов излучения более 500, а также зарегистрирована анизотропия сигнала комбинационного рассеяния света для данных полиморфных модификаций.

It is demonstrated that the surface-relief orientation in the form of one-dimensional gratings with a period of 1.20 ± 0.02 μm formed under processing of hydrogenated-silicon films by femtosecond laser pulses (1.25 μm) with an energy density of 0.15 J/cm 2 is determined by the direction of the polarization vector of the radiation and total laser exposure. Based on the results of the analysis of Raman spectra, the presence of a nanocrystalline phase of silicon with a volume fraction between 15 and 67% (depending on processing conditions) is detected. The observed processes of micro- and nanostructuring are caused by excitation of the surface plasmon–polaritons and nanocrystallization in the near-surface region in the field of high-power femtosecond laser pulses, respectively. In addition, formation of polymorph modifications of silicon Si-III and Si-XII under femtosecond laser processing with a number of pulses exceeding 500 is discovered. Anisotropy of the Raman signal for the above polymorph modifications is revealed.

Raman spectroscopy was applied to investigate laser-induced heating of silicon nanowires (SiNWs) formed by metal-assisted chemical etching of lightly boron-doped crystalline silicon (c-Si) wafers. Low-frequency shift of the Raman peak from 520.5 cm−1 to about 517 cm−1 for SiNWs with length of 40–65 µm under laser irradiation with wavelengths of 632.8 or 488 nm was observed, and it was explained by an increase in the average temperature of SiNWs on about 150 K for the laser intensity about 1 kW/cm2. The same photoinduced heating was confirmed by analyzing the ratio between the Stokes and anti-Stokes components of the Raman scattering. The obtained experimental data allow us to estimate the thermal conductivity coefficient of SiNW array ~0.1 W/(m K), which is three orders of magnitude smaller than that of c-Si. Furthermore, the Raman spectra of SiNWs under excitation with intensity above 0.2–0.5 kW/cm2 consisted of an additional low-frequency peak, which is related to an overheated subsystem of well spatially separated fine SiNWs up to 600–700 K. The observed strong photoinduced heating can be used for local laser-induced treatment of SiNWs and biomedical applications.

Crystalline boron has been prepared via high-pressure, high-temperature pyrolysis of decaborane, B10H14. We obtained α-tetragonal boron crystals at a pressure of 8–9 GPa and temperatures in the range 1100–1600°C and β-rhombohedral boron intergrowths at 3 GPa and 1200°C.

Sodium fullerides Na n C60 ( n = 2, 3) have been synthesized by a liquid phase reaction and investigated with X-ray diffraction (XRD), nuclear magnetic resonance (NMR), electron paramagnetic resonance, and differential thermal analysis. XRD data indicate that the crystal structure of Na 2 C 60 at 300 K is face centered cubic (FCC). A phase transition from primitive cubic to FCC crystal structure has been observed in this work in Na 2 C 60 fulleride at 290 K. The transition is accompanied by the step-like change of paramagnetic susceptibility. The crystal structure of Na 3 C 60 is more complicated than, and different from, what has been reported in the literature. A nearly seven-fold increase of paramagnetic susceptibility with increasing temperature has been observed in the Na 3 C 60 fulleride at 240–260 K. In the same temperature range, a new line at about 255 ppm appears in the 23 Na NMR spectrum, indicating a significant increase of electron density near the Na nucleus. The observed effect can be explained by a metal-insulator transition caused by a structural transition.

The structure and electron properties of Na n C60 (n = 2, 3) sodium fullerides synthesized from simple compounds in toluene were studied. It was shown that Na2C60 fulleride forms a face-centered cubic lattice at temperatures above 300 K. As the temperature is lowered, the phase transition to a structure with a simple cubic lattice takes place. The temperature dependences of the properties of Na3C60 with a more complex structure exhibit features that are presumably due to sodium atom redistribution in the Na3C60 fulleride lattice and the formation of sodium ion clusters.

Superconducting boron-doped diamond samples were synthesized with isotopes of B-10, B-11, C-13 and C-12. We claim the presence of a carbon isotope effect on the superconducting transition temperature, which supports the 'diamond-carbon'-related nature of superconductivity and the importance of the electron-phonon interaction as the mechanism of superconductivity in diamond. Isotope substitution permits us to relate almost all bands in the Raman spectra of heavily boron-doped diamond to the vibrations of carbon atoms. The 500 cm(-1) Raman band shifts with either carbon or boron isotope substitution and may be associated with vibrations of paired or clustered boron. The absence of a superconducting transition (down to 1.6 K) in diamonds synthesized in the Co-C-B system at 1900 K correlates with the small boron concentration deduced from lattice parameters.

Semiconductor structures of the type of butyl-substituted erbium monophthalocyanine and triphthalocyanine are studied by Raman spectroscopy. It is shown that, when the sandwich-like structure of the molecule incorporating two complexing atoms between the ligands is considered instead of the planar molecular structure with one ligand and one metal atom, a series of lines appears in the Raman spectrum. In this series, the wave numbers of the lines represent an arithmetic progression with the arithmetical ratio ∼80 cm −1 . It is suggested that this feature is due to the larger number of organic molecules per metal atom in the triphthalocyanine complex, and the four Raman peaks at the frequencies 122, 208, 280, and 362 cm −1 are the manifestation of slight out-of-plane vibrations of the phthalocyanine ligands.