Femtosecond optical nonlinearity of Au nanoparticles under their excitation in nonresonant relative to surface plasmon conditions

Nonlinear optical response of Au island films to femtosecond laser pulses is studied in the vicinity but not exactly at the surface plasmon absorption peak (λ _spr = 560 nm). The third-order nonlinear optical susceptibility is shown to be Reχ ⁽³⁾ = +1.7 × 10^?7 esu and Reχ ⁽³⁾ = +1 × 10^?7 esu at the wavelengths 800 and 460 nm, respectively. Kinetics of the optical nonlinear response has been studied for wavelengths 400 and 800 nm. It is believed that the origin of nonlinearity at the wavelengths is related to the free-electron heating in the conduction band and their further thermalization via electron–electron scattering, but at 400 nm the contribution to the nonlinear susceptibility because of interband d → s, p transitions is also possible.     

On the problem of the LO-TO splitting of the soft mode in CaTiO3

The dispersion analysis of the panorama reflection spectrum of ceramic calcium titanate has been performed following the additive and factorized dispersion models with the goal to reveal the degree of adequacy of each of these models for determining the dispersion parameters of phonon modes. The correspondence of longitudinal and transverse IR-active vibrations has been established for the cubic and orthorhombic phases. Giant LO-TO splitting of the low-frequency soft mode (700 cm^?1), which leads to the inversion of the frequencies of all other IR vibrations in this region, has been found. This result is in good agreement with first-principles calculations.     

Synthesis and properties of isopropylamine borane i-C3H7NH2 · BH3

Isopropylamine borane i-C₃H₇NH₂ · BH₃ was synthesized by the reaction of sodium tetrahydroborate NaBH₄ with isopropylamine hydrochloride in tetrahydrofuran followed by extraction with diethyl ether. Its synthesis conditions were determined and optimized. The compound was characterized by chemical analysis, IR spectroscopy, and differential thermal analysis.     

On the Possibility of using Vertical Receiving Arrays for Underwater Acoustic Communication on the Arctic Shelf

Acoustical Physics - Numerical simulation is applied to analyze the possibilities of using vertical receiving arrays covering the entire waveguide for underwater acoustic communication on the...     

Progress in development of Nuclotron accelerator complex

The Nuclotron superconducting synchrotron was constructed in 1987–1992 [1]; it is the world’s first synchrotron based on fast cycling “window frame” electromagnets with a superconducting coil. For a design field of dipole magnets of 2 T, the magnetic rigidity is 45 T m, which corresponds to the energy of heavy nuclei (for example, gold) of 4.5 GeV/nucleon. The Nuclotron accelerator complex is currently being upgraded (the Nuclotron-M project); this upgrade is considered a key part of the first stage of fulfilling the new Joint Institute for Nuclear Research (JINR) project: the Nuclotron-based Ion Collider fAcility and Multi-Purpose Detector (NICA/MPD). The most important task of this new project is the preparation of basic Nuclotron systems for its reliable operation as part of the NICA accelerator complex. Basic results of activity on the project, which started in 2007, are presented and the results of the last Nuclotron runs are analyzed.     

Centrifugal fragmentation of a dinuclear system in the process of its evolution toward a compound nucleus

The centrifugal fragmentation of a dinuclear system in the process of evolution toward a compound nucleus is examined. If the angular momentum in the collision of primary nuclei is quite high, centrifugal forces become dominant at the final stage of the evolution of the dinuclear system formed, causing the decay of this dinuclear system to two strongly asymmetric nuclear fragments. Experimental data in which this specific nuclear process manifests itself are presented. Centrifugal fragmentation makes it possible to reveal the cluster facet of the evolution of a dinuclear system toward a compound nucleus. The possibility of this fragmentation process is a logical consequence of the concept of a dinuclear system for the complete fusion of nuclei.