Spectra and structure of energy levels of Pr3+ in crystals of yttrium and gadolinium oxyorthosilicates

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 6, pp. 123–129, November–December, 1995.     

Spectral reflection characteristics of spruce needles and leaves of trees in the zones with industrially polluted air

We analyze the results of laboratory measurements for the reflection spectra of spruce needles and maple leaves from zones with different degrees of air pollution by SO₂ and NO_x oxides. The calculated first derivatives and vegation indices are discussed. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 6, pp. 789–792, November–December, 1997.     

The effect of complexing processes on energy transfer Tl+→Gd3+ and Tl+→Tb3+ in glass

T. Shevchenko Kiev University, 252022 Kiev, Pr. Akad. Glushakova, 6, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 3, pp. 192–196, May–June, 1995.     

Spectroscopic study of the interaction between porphyrin and chlorin molecules of opposite charge in solutions

Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, Minsk, 220072, 70, F. Skorina Ave., Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 2, pp. 152–163, March–April, 1995.     

Spectral-luminescence and lasing properties of several morpholine derivatives of naphathalimide in different solvents

The spectral-luminescence properties, lasing ability, and time-resolved gain spectra of three morpholine derivatives of naphthalimide (substituted in position 4) in polar (ethanol and dimethylformanide) and nonpolar (diethyl ester and toluene) solvents are investigated. It is found that rotation of the morpholine group about the single bond connecting the group with the rest molecule takes place, which results in a shift of the gain spectrum towards the longwave region and decrease of the fluorescence quantum yield. Deceased. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 5, pp. 603–606, September–October, 1997.     

Ab initio molecular dynamics investigations of structural, electronic and dynamical properties of water in supercritical carbon dioxide

Ab initio molecular dynamics simulations of a solitary perdeuterated water molecule solvated in supercritical carbon dioxide have been performed along an isotherm at three different densities. Electron donor-acceptor interactions between the oxygen atom of water and the carbon atom of CO₂ as well as hydrogen bonded interactions between the two molecules have been shown to play a dominant role in the solvation. The mean dipole moment of the water molecule increases with the density of the solution, from a value of 1.85 D at low density to around 2.15 D at the highest density. The increase in the solvent density causes the water molecule to exhibit a range of behavior, from a free molecule to one that interacts strongly with CO₂. A blue shift in the bending mode of water has been observed with increasing solvent density. The carbon dioxide molecules which are present in the first neighbor shell of water are found to exhibit larger propensity to deviate from a linear geometry in their instantaneous configurations.      

Electronic absorption and emission spectral data and fluorescence quantum yields of bridgedp-oligophenylenes,bi- to deciphenyls,and related furans and carbazoles

Absorption and fluorescence emission spectral data, as well as fluorescence quantum yields (_f), were determined for 41p-oligophenylene compounds containing 2–6, 8, and 10 benzene rings. Of 29 compounds containing carbon-bridged rings (fluorenes), 28 were dialkylated on each bridge for improved solubility and photostability. Absorption maxima for oligophenylenes were observed at wavelengths as long as 366 nm, emission maxima to 437 nm, and molar extinction coefficients () as large as 153,000 L/mol-cm; all three exceeded predicted maximum values for the corresponding unbridged oligophenylenes. The substitution of furan for benzene or carbazole for a fluorene (two examples each) bathochromically shifted absorption and emission maxima. Dialkylated carbon bridges bathochromically shifted absorption and emission maxima, and lowered _f in biphenyl and in one terphenyl analogue, but appeared to cause no diminution of _f in higher oligophenylenes. Bis(2-methoxyethyl) substitution on the bridges, incorporated to provide solubility in polar solvents, lowered _f in all examples. Tertiary alkyl substituents on terminal rings bathochromically shifted the absorption and emission maxima and generally increased _f. The loose bolt effect, which lowers _f in mononuclear substituted benzenes, may operate in 9,9-dialkylfluorenes, but not in 2,7-di-t-butylfluorene or in higher oligophenylenes. Cyclic ether and methoxy substituents as auxofluors on terminal rings generally bathochromically shifted absorption and emission maxima and increased and _f. Cyano substituents bathochromically shifted absorption and emission maxima, and increased , but lowered _f slightly.     

Effect of spontaneously generated coherence on EIT and its refractive properties in four- and five-levels systems

The effects of spontaneously generated coherence (SGC) and phases of optical fields on the phenomenon of electromagnetically induced transparency (EIT) are investigated in a four-level inverted-Y system and in a five-level K-type system under various parametric conditions in order to demonstrate controllability of the EIT, dispersion properties, and group velocity in such systems. Non-zero second-order susceptibility in both systems is due to the SGC effect. The experimental viability of the model in semiconductor quantum well systems is also discussed.