Dark resonances in 87Rb atomic vapors interacting with the field of copropagated linearly polarized waves of various frequencies

The results of theoretical and numerical analysis of resonances of coherent population trapping in ⁸⁷Rb atomic vapors, obtained using copropagated linearly polarized waves, are presented. Various schemes for exciting dark resonance are compared with a view to obtaining a new-generation small-size quantum frequency standard.     

Thermal oxidation of nonstabilized and stabilized polymers and chemiluminescence

The chemiluminescence under isothermal and nonisothermal conditions accompanying the oxidation of some polymers (polyolefins, polyamides, and polysaccharides) has been examined from the viewpoint of its relationship with the rate of oxidation. The chemical structure of a given type of polymer plays a decisive role in the resulting shape of the chemiluminescence curves. In the presence of an antioxidant, the inhibition periods of oxidation are shifted to longer times and/or higher temperatures. This shift is directly proportional to the type and concentration of stabilizer. Attention has also been paid to the impact of the average molar mass on the oxidizability of the macromolecular material. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 648–660, 2004     

Chemiluminescence - A Novel Method in the Research of Degradation of Paper. I. The Effect of Light on Stacked Sheets of Paper

Statistical scission of cellulose macromolecules leading to the negative changes in mechanical properties of the paper has been quantified on irradiated stacks of newsprint papers. Attention has been paid to comparison of changes occurring in respective sheets of the stack. The correlation of the results of non-isothermal chemiluminescence method from which the rate constant of paper oxidation has been determined for 105 °C with the changes of carbonyl groups concentration, pH and double folds has been outlined.     

Thermal Oxidation and Its Relation to Chemiluminescence from Polyolefins and Polyamides

Chemiluminescence (CL) from oxidation of polypropylene, polyethylene and polyamide has been compared and kinetic parameters based on the simplified kinetic scheme involving both bimolecular decomposition of hydroperoxides as an initiating event and correction for the oxidation spreading were determined. Induction times of oxidation determined from the autocatalytic shape of chemiluminescence intensity-time runs increase with an increasing initial molar mass of polypropylene within low molar masses up to 180 kDa regardless of the route of the polypropylene synthesis. The more complex chemiluminescence patterns in case of polyamides may be related with an increase of initially present defect structures including the terminal amino groups.     

Adiabatic Raman polariton in a Bose condensate

The Raman interaction of optical fields with a Bose condensate is studied in the adiabatic regime. A superposition of operators is found — one annihilating an atom in a metastable state and the other annihilating a photon in resonance with a transition from the ground state to an excited state — which is an adiabatic invariant of the problem (Raman polariton). Possible applications for Bose-condensate diagnostics and development of atomic lasers are proposed. Pis’ma Zh. éksp. Teor. Fiz. 64, No. 7, 473–477 (10 October 1996)     

Chemiluminescence in thermo-oxidation of polypropylene

Chemiluminescence in thermo-oxidation of polypropylene was interpreted, noting its course with time at different temperatures and the corresponding spectra. The light emission was attributed to decomposition of α-ketone-hydroperoxides and to chain oxidation of polymer proceeding via secondary peroxy radicals.     

Contribution of adsorption to rentension data in capillary gas chromatography part II. Non-polar stationary phases

Summary The influence of adsorption on the dependence of retention data upon film thickness of the non-polar stationary phases OV-101 and Apiezon L coated on glass (series of capillary columns with non-deactivated and Carbowax 20 M deactivated surface) and fused silica has been studied. Limiting values of Kovats indices, I, of solutes which exhibit tendency to hydrogen bonding are calculated for each series of columns.Presented at the 14th International Symposium on Chromatography London, September, 1982     

Structural factor for Bose-Einstein double-component condensate

The structural factors for the single-and double-component Bose-Einstein condensates of neutral atoms in a spherically symmetric harmonic trap are derived. The approach adopted in this paper is applicable in the low excitation energy limit, where the well-known Stringari dispersion relation is valid. Our expression is compared with the quasi-classical one, which is shown to overestimate the structural factor. It is argued that the second component first splits the frequency of collective condensate oscillations, which corresponds to the energy transferred by scattering, into two branches and then multiplies the single-component structural factor by some coefficient that can be greater than unity. The analysis is used to estimate the properties of an experimentally implemented double-component condensate of ⁸⁷Rb atoms.     

Nonlinearity effects in wave propagation in multicomponent Bose-Einstein condensates

We consider a spinor Bose-Einstein condensate in its polar ground state. We analyze magnetization waves of a finite amplitude and show that their nonlinear coupling to density waves dramatically changes the dependence of the frequency on the wave number. On the contrary, the density wave propagation is much less modified by nonlinearity effects. A similar phenomenon in a miscible two-component condensate is also studied.