Theory of absorption and amplification spectra of a weak electromagnetic field by two-level quantum systems

A theory is developed of the absorption and amplification spectra of a weak (probe) electromagnetic field (EMF) by open two-level quantum systems in a strong quasiresonant EMF, assuming separability of the triplet spectrum components. The theory describes the intensity and the form of the spectral lines for arbitrary intensities and detunings of the strong EMF, and also the dependence of the parameters of the adiabatic relaxation on the frequency of the weak EMF. The influence of nonlinear dynamic effects (NDE) due to the dependence of the relaxation on the EMF parameters on the shape of the spectral lines is investigated. It is shown, in particular, that under certain conditions the NDE can lead to a nonlinear dynamic transformation of the dispersion of the sideband dispersion lines into Lorentzian lines and to a considerable increase of the absorption in the central region of the spectrum. Particular attention is paid to an investigation of the NDE on the characteristics of the central component of the spectrum. Methods and results of an investigation of the spectra in a basis of unperturbed wave functions in in a basis of dressed states are compared.Radiophysics Division, Lebedev Physics Institute. Translated from Preprint No. 117 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1990.     

Absorption and fluorescence spectra and structure of the Höchst-33 258 dye

Using the semiempirical quantum chemical PM3 and CNDO/S3 methods, we have calculated the spatial and electronic structure and the absorption spectra of the Höchst-33 258 fluorofore (I) and some model compounds in various protonated forms. The low-frequency transition is characterized by a displacement of electron density along the long molecular axis toward the phenyl ring and leads to an increased proton affinity of the imidazole cycle. The quenching of the fluorescence of I in a neutral aqueous solution is explained by the formation of a bipolar form as a result of the proton transfer in a dimeric associate of molecules I. In going from aqueous to alcoholic solutions, fluorescence ignition of I was found experimentally.Institute of High-Molecular Compounds, Russian Academy of Sciences. St. Petersburg Technological Institute. Translated fromZhurnal Strukturnoi Khimii, Vol. 34, No. 6, pp. 31–42, November–December, 1993.Translated by L. Smolina     

Synthesis,structure, and acid-base characteristics of enaminones of the barbituric acid series

Enaminones were obtained by a tricomponent condensation of barbituric acids, aniline and triethyl orthoformate. The acid-base properties, PMR, UV and IR spectra of 5-anilinomethylene- and 1,3-dimethyl-5-anilinomethylenebarbituric acids are discussed. The properties of these compounds conform with a bipolar structure, in which the positive charge is distributed over the exocyclic part of the molecule, while the negative charge is distributed on the -dicarbonyl fragment of the heterocyclic ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 952–956, July, 1988.     

Solution of the problem of charge motion in crossed electric and magnetic fields

Using the method of first integrals, we find an exact solution for the relativistic motion of a charge in orthogonal and uniform electric and magnetic fields with respect to laboratory time and for any value of the dimensionless governing parameter equal to the ratio of the magnetic field strength to the electric field strength.     

Microfocus X-Ray Tubes with a Silicon Autoemission Nanocathode as an X-Ray Source

To develop nanostructures with extremely low spatial resolution (to 10 nm and below), a new concept of the use of arrays of microfocus X-ray tubes based on field emission silicon nanocathodes is proposed. A new λ-tunable microfocus source of X-ray radiation, based on a thinfilm transmission target with field emission nanocathode with tunable wavelength, is proposed. The possibility of decreasing the exposed area size to 20 nm and smaller by varying the tube blocking voltage is shown. The use of these X-ray sources opens a new way of developing maskless X-ray lithography.     

Carbalkoxilation of polyethylene polyamines with dialkyl carbonates

Russian Chemical Bulletin - The reaction of carbalkoxylation of polyethylene polyamines (PEPA) with various dialkyl carbonates, including fluorine-containing ones, was studied in order to obtain...     

Sorption Selectivity of Palladium(II) by Poly(N-2-Sulfoethylallylamine) under Static and Dynamic Conditions

Russian Journal of Applied Chemistry - The process of Pd(II) sorption from hydrochloric acid solutions was studied in the pH range of 0.5–5.0 in the presence of Pt(IV) and a number of...     

Addition of the oxirane derivatives to CO2 catalyzed by Lewis bases under mild conditions

Russian Chemical Bulletin - The addition of the oxirane derivatives to CO2 was found to occur without Lewis acid involvement but requires the presence of the Lewis base. The reaction was carried...     

Preparation of a sorbent for metal ions based on N-(5-methylimidazol-4-ylmethyl) chitosan with medium degree of substitution

A procedure was developed for preparing a heterocycle-containing chelating amino polymer, N-(5-methylimidazol-4-ylmethyl) chitosan, by polymer-analogous transformations of chitosan in reaction with 4-chloromethyl-5-methylimidazole. The procedure allows synthesis of the polymer with the degree of substitution of up to 0.8, with simultaneous formation of the cross-linked structure. The structure of the polymers prepared was proved by IR and ¹³C NMR spectroscopy. The ability of N-(5-methylimidazol-4-ylmethyl) chitosan with the degree of substitution of 0.54 to sorb Cu²⁺ and Ni²⁺ ions was evaluated. According to the sorption isotherms, the sorption capacity of this derivative exceeds that of the unmodifi ed polymer by a factor of 5.     

Mo-based EUV multilayer filters with enhanced thermal stability

New Mo-based multilayer structures are proposed, and sample free-standing filters 160 mm in diameter with a transparency of 71% at a wavelength of λ = 13.5 nm are described. The enhanced thermo-oxidative stability of filters with Mo layers is demonstrated as opposed to Zr-based films. It is shown in particular that Mo-based filters can withstand vacuum heat annealing at 800°C for three hours without any optical and structural changes.