Nonlinear regime of the excitation of a surface electromagnetic wave on the silicon surface by an intense femtosecond laser pulse

A surface electromagnetic wave has been excited on an atomically smooth silicon surface by an intense infrared femtosecond laser pulse as a result of its self-diffraction on a microscale short-lived optical inhomogeneity of the excitation region rather than on the roughness of its surface relief. This wave has been visualized in the form of the pattern of its interference with the same incident infrared ultrashort pulse, which corresponds to the instantaneous surface dielectric constant grating (reflection), as well as the resulting surface relief grating, using time-resolved far-field optical reflection microscopy.     

Building Symmetric Designs With Building Sets

We introduce a uniform technique for constructing a family of symmetric designs with parameters (v(q ^m+1-1)/(q-1), kq ^m ,q ^m), where m is any positive integer, (v, k, ) are parameters of an abelian difference set, and q = k ²/(k - ) is a prime power. We utilize the Davis and Jedwab approach to constructing difference sets to show that our construction works whenever (v, k, ) are parameters of a McFarland difference set or its complement, a Spence difference set or its complement, a Davis–Jedwab difference set or its complement, or a Hadamard difference set of order 9 · 4 ^d , thus obtaining seven infinite families of symmetric designs.     

Quantum-Chemical Investigation of Pentafluorophenylxenonium and (Heptafluorocyclohexa-1,4-dien-1-yl)xenonium Cations and Related Molecules

Quantum-chemical DFT B3LYP/(6-311G** &; Xe 3-111G*) package was used for calculation of structural parameters and NMR spectra of cations [MeCN ? XeC₆F₅]⁺, [XeC₆F₅]⁺ and [XeC₆F₇]⁺ free and in acetonitrile as solvent (solv., C-PCM). Structures and relative energies of hypothetical intermediates (perfluorocyclohexa-3-en-1-yliden)xenon(II) XeC₆F₈(solv) and (perfluorocyclohexa-3-en-1,1-diyl)xenon(0) Xe: C₆F₈(solv) in the reaction of cation [XeC₆F₇]⁺(solv) with anion F^?(solv), and those of perfluoro(3-methylenecyclopentene), the final compound formed at decomposition of [XeC₆F₇]⁺ with fluorides in acetonitrile, were determined.     

Synthetic magnetic opals

We present studies of novel nanocomposites of BiNi impregnated into the structure of opals as well as inverse opals. Atomic force microscopy and high resolution elemental analyses show a highly ordered structure and uniform distribution of the BiNi filler in the matrix. These BiNi-based nanocomposites are found to exhibit distinct ferromagnetic-like ordering with transition temperature of about 675 K. As far as we know there exists no report in literature on any BiNi compound which is magnetic.     

A technique for constructing divisible difference sets

An (m, n, k, ₁,₂) divisible difference set in a groupG of ordermn relative to a subgroupN of ordern is ak-subsetD ofG such that the list {xy^–1:x, y D} contains exactly ₁ copies of each nonidentity element ofN and exactly ₂ copies of each element ofG N. It is called semi-regular ifk > ₁ and k²=mn₂. We develop a method for constructing a divisible difference set as a product of a difference set and a relative difference set or a difference set and a subset ofG which we call a relative divisible difference set. The method results in several parametrically new families of semi-regular divisible difference sets.     

A technique for constructing non‐embeddable quasi‐residual designs

We propose a technique for constructing two infinite families of non‐embeddable quasi‐residual designs as soon as one such design satisfying certain conditions exists. The main tools are generalized Hadamard matrices and balanced generalized weighing matrices. Starting with a specific non‐embeddable quasi‐residual 2‐(27,9,4) design, we construct for every positive integer m a non‐embeddable 2‐(3^m,3^m?1,(3^m?1?1)/2)‐design, and, if r_m=(3^m?1)/2 is a prime power, we construct for every positive integer n a non‐embeddable design. For each design in these families, a symmetric design with the corresponding parameters is known to exist. © 2002 Wiley Periodicals, Inc. J Combin Designs 10: 160–172, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.900     

Breaking of the Axial Symmetry of Terahertz Radiation from Single-Color Filament Plasma

JETP Letters - Two-dimensional distribution patterns of terahertz radiation generated in a laser single-color filament plasma are measured at several frequencies. In the low-frequency region...