Kinetics of the quenching of N2-O2-NO mixtures

A simple method is proposed to estimate nitrogen oxide yield after quenching of the equilibrium mixture, the cooling rate being hyperbolical or exponential.     

Quantum Hall activation gaps in bilayer graphene

We have measured the quantum Hall activation gaps in bilayer graphene at filling factors $\nu =\pm 4$ and $\nu =\pm 8$ in high magnetic fields up to 30 T. We find that energy levels can be described by a 4-band relativistic hyperbolic dispersion. The Landau level width is found to contain a field independent background due to an intrinsic level broadening and a component which increases linearly with magnetic field.     

Pitt and Boas inequalities for Fourier and Hankel transforms

We prove Pitt and Boas inequalities for products of radial functions and spherical harmonics in Rⁿ${\mathbb{R}}^n$. In the process, we obtain upper and lower estimates of the operator norm of the Hankel transform with power weights. Our inequalities are sharp in some specific cases.     

Weak localization in graphene flakes

We show that the manifestation of quantum interference in graphene is very different from that in conventional two-dimensional systems. Because of the chiral nature of charge carriers, it is not only sensitive to inelastic, phase-breaking scattering, but also to a number of elastic scattering processes. We study weak localization in different samples and at different carrier densities, including the Dirac region, and find the characteristic rates that determine it. We show how the shape and quality of graphene flakes affect the values of the elastic and inelastic rates and discuss their physical origin.     

Optical Properties of Silver Nanoclusters Synthesized in Surface-Grafted Polyacrylic Acid at Different Grafting Densities

Optics and Spectroscopy - Fluorescent silver nanoclusters immobilized on a plastic substrate are obtained by photoinduced template synthesis using polyacrylic acid chemically grafted to the...     

Sorption of Zinc Ions by a Nonwoven Polypropylene Material Modified with Poly(acrylic acid) Grafted to the Fiber Surface: The Role of Grafting Density and Hydrogen Bonds

A microfiber carboxylic cationite is prepared via the photoinduced polymerization of acrylic acid on the surface of nonwoven polypropylene material. Changes in the amount of the graft polymer (grafting density) and in the strength of hydrogen bonds between its carboxyl groups, depending on the polymerization time, are investigated by attenuated total internal reflectance FTIR spectroscopy. The sorption properties of the obtained ionite in the acidic (COOH) and salt (COONa) forms with respect to Zn²⁺ ions at various grafting densities are studied. The sorption capacity of the investigated cationite in its salt form is higher than that in the acidic form, and this difference increases quickly with the grafting density. The data of IR spectroscopy showed that this behavior is caused by the formation of stronger hydrogen bonds between COOH groups of the grafted polyacrylic acid, complicating their ionization and, thus, preventing the ion exchange.     

Selective spectroscopy of tunneling transitions between the Landau levels in vertical double-gate graphene–boron nitride–graphene heterostructures

The spectral and total electron densities of states in two-dimensional FeAs clusters, which simulate iron-based superconductors, have been calculated using the generalized quantum Monte Carlo algorithm within the full two-orbital model. Spectra have been reconstructed by solving the integral equation relating the Matsubara Green’s function and spectral density by the method combining the gradient descent and Monte Carlo algorithms. The calculations have been performed for clusters with dimensions up to 10 × 10 FeAs cells. The profiles of the Fermi surface for the entire Brillouin zone have been presented in the quasiparticle approximation. Data for the total density of states near the Fermi level have been obtained. The effect of the interaction parameter, size of the cluster, and temperature on the spectrum of excitations has been studied.