Supramolecular organization of meso-substituted derivatives of tetraphenylporphine in thin films

Films of meso-substituted derivatives of tetraphenylporphine substituted in the paraor ortho-positions of the phenyl rings with alkoxy groups (-OC₄H₉ or -OC₁₆H₃₃) and films of their metal complexes are prepared using the Langmuir-Schaefer (LS) method. The effect of the molecular structure on the supramolecular organization of thin films is determined. The films are obtained by transferring layers of the compounds from the surface of the water onto silicon substrates using the Langmuir-Schaefer technique. The structures of the one-component LS films of the investigated compounds are studied by the small-angle X-ray scattering method, and also the lattice periodicities are calculated. The supramolecular organization of the meso-substituted tetraphenylporphine derivatives is modeled and refined by means of the X-ray diffraction method. When Ni or Cu serve as chelating metal, it is found that the macrocycle-macrocycle interaction is so large that it leads to violation of the molecular linearity, i.e., the lateral substituents are folded toward the macrocycle, reducing the area occupied by the structural units.     

Spatial distribution of defects produced by boron ion implantation of silicon

A simple technique for the study of the spatial distribution of the damage produced by ion implantation of silicon has been developed. The damage depth distribution for 40 keV boron ions in silicon has been studied at irradiation doses from 7 × 10¹¹ to 3.9 × 10¹⁴ ions/cm² and the relative defect peak depth R _d/R _p = 0.85 determined. An increase of layer conductivity as the surface part of the implanted layer is removed has been revealed. This effect is caused by the presence of radiation defects in the surface region of the layer. The “electrical” cluster diameter is about 28 A and the overlapping cluster dose is close to 1 × 10¹³ ions/cm².     

Semiperfect Category-Graded Algebras

We introduce the notion of algebras graded over a small category and give a criterion for such algebras to be semiperfect.     

Kinetics of atoms in a bichromatic field

The kinetics of atoms in a bichromatic field is considered. Analytic solutions are obtained for the force, friction coefficient, and diffusion coefficient in the model of a two-level atom without limitations imposed on the intensity of light fields. This effect is observed in the domain of global minima and maxima of the optical potential (i.e., at points where the relative phase of two standing waves is ? = 0, π/2.     

Temperature dependence of the conductance and capacitance of langmuir films of liquid crystals

Langmuir films of various thicknesses, fabricated based on liquid crystals, have been studied. Previously, a structural phase transition at a temperature of ～75°C was detected for these films. To determine the nature of this transition, the temperature dependences of the capacitance and conductance of the metal-Langmuir film-metal structures have been measured. The results obtained suggest that the ferroelectric phase in the studied samples exists beginning with one monolayer. The length of the temperature interval in which the phase transition is observed indicates a film structure imperfection.     

On the measure of large values of the modulus of a trigonometric sum

We study the connection between the additive structure of a finite set A⊂Z$A\subset \mathbb{Z}$ and the measure of large values of the modulus of a trigonometric sum.     

Magnetooptical force in the resonance field formed by elliptically polarized light waves

The screening of the Coulomb interaction is studied with regard to Friedel oscillations in multicomponent electron plasma structure. A double quantum well (QW) and a superlattice are considered. The groundstate energy of a donor (exciton) in a double quantum well is calculated by a variational method as a function of the population of subbands.     

Carboxyboronate: A Versatile C1 Building Block

The synthesis and applications of carboxy‐MIDA‐boronate, a novel C1 building block, are described. This molecule is accessible via a ruthenium tetraoxide‐mediated cleavage of commercially available ethynyl‐MIDA‐boronate. In the course of this study, carboxy‐MIDA‐boronate was found to possess ambident reactivity towards nucleophiles. Carboxylic acid derivatization produces a broad range of previously unknown carbamoyl‐, oxycarbo‐ and thiocarboboronates. Carboxy‐MIDA‐boronate and its derivatives undergo condensations to access borylated heterocycles with boron at positions that are difficult to access using alternate methods. The resulting heterocycles participate in the Suzuki–Miyaura cross‐coupling reaction, enabling entry into diverse bis(heteroaryl) motifs. The carbon monoxide‐releasing capacity of carboxy‐MIDA‐boronate was also examined and applied in palladium‐catalyzed carbonylation.     

Optical lattice induced light shifts in an yb atomic clock

We present an experimental study of the lattice-induced light shifts on the (1)S(0) --> (3)P(0) optical clock transition (nu(clock) approximately 518 THz) in neutral ytterbium. The "magic" frequency nu(magic) for the 174Yb isotope was determined to be 394 799 475(35) MHz, which leads to a first order light shift uncertainty of 0.38 Hz. We also investigated the hyperpolarizability shifts due to the nearby 6s6p(3)P(0) --> 6s8p(3)P(0), 6s8p(3)P(2), and 6s5f(3)F(2) two-photon resonances at 759.708, 754.23, and 764.95 nm, respectively. By measuring the corresponding clock transition shifts near these two-photon resonances, the hyperpolarizability shift was estimated to be 170(33) mHz for a linear polarized, 50 microK deep, lattice at the magic wavelength. These results indicate that the differential polarizability and hyperpolarizability frequency shift uncertainties in a Yb lattice clock could be held to well below 10(-17).     

Polystyrene-Based Composites with Aluminosilicate Inclusions of Different Shapes

Technical Physics - Samples of composites based on polystyrene with addition of halloysite nanotubes, mica, and montmorillonite aluminosilicates are obtained and the influence of these fillers on...