Amplified spontaneous emission in dye-laser systems for single photon amplification

A longitudinally pumped dye-laser amplifier is numerically investigated for the amplification of a very low intensity signal (as low as one photon per pulse), which is easily hindered by the simultaneous amplification of spontaneous emission. From the relevant set of coupled rate equations for population and photon fluxes the spatial dependence of these quantities is accounted for. The equations are solved numerically in some significant practical situations. The results describe the dependence of the amplified-spontaneous-emission (ASE) output flux on the pumping rate, on the spectral narrowing process and on the total spontaneous emission for a pulse in the selected angular width. The performance of dye-laser amplifiers is described by the same set of equations, and the gain characteristics of such systems are analyzed as functions of the pumping rate.     

Isolement et identification de l'évernine dans la «mousse de chêne» (Evernia prunastri (L.) Ach.). 2e Communication

Isolation and identification of evernine in ‘Oakmosse’ (Evernia prunastri (L. ) Ach.). A new depside, evernin ( 1 ), has been found in the lichen Evernia Prunastri (L. ) Ach. The determination of the structure and the spectral parameters of 1 , especially the ¹³C-NMR. spectrum, are described.     

Isolement et identification de composés phénoliques et monoterpéniques de la mousse de chêne (Evernia prunastri (L.) Ach.)

The composition of different oakmoss extracts was investigated by combined gas chromatography/mass spectrometry. A series of 38 compounds – especially phenol derivatives and monoterpenes – was identified, 22 of which have not yet been reported as constituents of oakmoss.     

A proton NMR study of water in hydrated sodium β-alumina

Proton nmr study of hydrated sodium β-alumina reveals a Pake doublet spectrum due to stationary water molecules. As the temperature is increased from -196C to 192C, linewidth changes indicate that the stationary protons sense the increasingly rapid motion of nearby sodium nuclei and other protons. The interproton spacing computed from the spectra was found to be 1.7A.     

Characterization of raw and stabilized waste in relation to toxic metals mobility in realistic landfilling scenarios

Toxic metal release in simple leaching tests has been studied in this paper to assess waste behaviour in realistic landfilling scenarios. The waste is a galvanic sludge, raw or cement stabilized. Six different leachants were taken into account: distilled water, CO2-saturated solution, Olsen solution, Mehlich No. 3 solution, acid or alkaline soil circulating solution. Dynamic leaching tests of different duration were used for raw and stabilized waste. The results have shown that, with the exception of Mehlich No. 3 solution, when the waste comes into contact with waters of composition similar to that of the solutions studied, the potential environmental contamination should not be of concern.     

A Hartogs type theorem for separately Cr functions

The main step in the proof of Hartogs’ theorem on separate analyticity (see [3], [4], [5]) consists in showing that if a function f defined in Δ × Δ is holomorphic for |z ₂| < ε and separately holomorphic in z ₂ when z ₁ is kept fixed, then it is jointly holomorphic; the normal convergence of the Taylor series of f is obtained through the celebrated Hartogs’ lemma on subharmonic functions.     

Upper and lower bounds for higher order eigenvalues of some semilinear elliptic equations

We prove upper and lower bounds on the eigenvalues (as the norm of the eigenfunction tends to zero) in bifurcation problems for a class of semilinear elliptic equations in bounded domains of R^N. It is shown that these bounds are computable in terms of the eigenvalues of the associated linear equation.     

Raman phonon spectra and lattice dynamics of 9,10-dinitroanthracene under pressure

Abstract

Raman phonon spectra of 9, 10-dinitroanthracene have been recorded in the pressure range 0-6GPa. No phase transition is detected up to the maximum pressure studied. Quasi Harmonic Lattice Dynamics calculations, based on an atom-atom potential previously modeled on homologous 9,10-disubstituted anthracenes, have been performed. The optimized potential was used to calculate the equilibrium geometry and the lattice phonon frequencies as a function of pressure. The calculated structure at ambient conditions closely resembles the experimental one. The calculated phonon frequencies show a good agreement with the experimental values at all pressures measured.