100-TW femtosecond laser based on parametric amplification

In experiments on the parametrical amplification of femtosecond pulses in wide-aperture DKDP crystals, a power of more than 100 TW has been reached, which is much higher than the record level achieved in such lasers. The energy efficiency obtained for the parametric amplifier is equal to 27%. The energy of a 72-fs pulse is equal to 10 J.     

Wave diagnostics of plasmas using a dielectric waveguide

We study the dispersion characteristics of a planar dielectric waveguide in a magnetized plasma. A method is proposed to determine the parameters of an RF discharge plasma by comparing experimental and theoretical dependences of the transmission coefficient of the sounding microwave signal through a dielectric waveguide on the external magnetic field. Experimental tests showed good agreement between the results of measurements of the plasma density in the discharge by the method proposed and using Langmuir probes. The possibilities of using metal-oxide (dielectric)-semiconductor (MOS) structures as tunable rejector filters, phase rotators, and modulators are discussed. N. I. Lobachevsky State University of Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 3, pp. 215–224, March, 1999.     

Morse parameters for the interaction of metals with graphene and silicene

We present Morse parameters for the interaction of graphene and silicene surfaces with the atoms of practically important metals Ni, Ag, and Li. The parameters' values are derived from the dispersion corrected density functional calculations. Two possible cases of $s{p}^2$-hybridized C/Si atoms in the unbroken graphene/silicene sheets and sp-hybridized atoms near the vacancies are considered. Proposed Morse parameters' sets reproduce binding energies, bond lengths and oscillation frequencies of metal atoms adsorbed on the hollow positions over the rings of C₆₀ and Si₆₀ fullerenes. They also reproduce well the same quantities for the substituted C₅₉M and Si₅₉M fullerenes (M?=?Ni, Ag, Li).     

Simulation of metastable CL-20 cluster structures

Ensembles of C₆H₆N₁₂O₁₂ (CL-20) clusters with different types of intercluster bonds have been studied theoretically. The stability of such cluster has been investigated and the heights of potential barriers preventing their decomposition or isomerization have been determined by means of quantum-mechanical calculations based on the density functional theory and nonorthogonal tight-binding model. From the analysis of molecular dynamics data and potential energy hypersurface of these metastable configurations, it has been established that dimers and tetramers of CL-20 clusters are characterized by sufficiently high kinetic stability, which suggests the theoretical possibility of creation of high-energy covalent crystals on their basis.     

New scheme of a petawatt laser based on nondegenerate parametric amplification of chirped pulses in DKDP crystals

The ultra-broadband phase matching was experimentally observed in a DKDP crystal upon parametric amplification of signal radiation with a wavelength of 911 nm in a pump field with a wavelength of 527 nm. The original scheme was used to excite the first parametric amplification stage by chirped pulses of idler radiation with a wavelength of 1250 nm. The saturated gain of a three-stage parametric amplifier was equal to 10⁸.     

Influence of Mechanical Stretching on Adsorption Properties of Nitrogen-Doped Graphene

This paper presents the results of quantum chemical modeling of chemisorption of atomic hydrogen and epoxy, carboxyl, and hydroxyl functional groups on nitrogen-doped graphene. It is shown that the substitutional nitrogen atom does not bind to adsorbing groups directly, but significantly increases the adsorption activity of neighboring carbon atoms. Mechanical stretching of doped graphene reduces the adsorption energy of all the aforementioned radicals. This reduction is significantly greater for the epoxy group than for the other functional groups. The results obtained confirm that, upon a sufficient stretching of a nitrogen-doped graphene sheet, the dissociation of molecular hydrogen and oxygen with subsequent precipitation of the resulting radicals onto graphene can be energetically favorable.

     

Stone–Wales Bilayer Graphene: Structure,Stability, and Interlayer Heat Transfer

JETP Letters - The structure, stability, and interlayer heat transfer of Stone–Wales bilayer graphene have been studied within a nonorthogonal tight binding model. The most stable...     

The study of thiazole adsorption upon BC2N nanotube: DFT/TD-DFT investigation

Structural Chemistry - Herein, we evaluated the adsorption of thiazole over the surface of BC2N nanotube using PBE and M06-2X functionals and 6-311G** standard basis set. We considered one and two...