Z. Mazurak

Radiative and non-radiative transitions in ErP5O14 single crystals

Abstract The radiative and non-radiative transitions from excited states of ErP5O14 were studied on the basis of the Judd-Ofelt theory and experimental data. It was shown that the non-radiative relaxations, predominantly multiphonon emission, are very effective in the depopulation of excited states of erbium in erbium pentaphosphate crystals. The concentration quenching of erbium fluorescence is found to be small.

Absorption and fluorescence intensity analysis of Pr3+ in LiPrP4O12 crystal

Abstract Absorption and fluorescence spectra of LiPrP 4 O 12 crystal were measured with high accuracy. Using the Judd-Ofelt theory the Ω λ parameters and probabilities of the radiative transitions for the 3 P 0 , 1 D 2 , excited states were calculated. From the presented analysis of the fluorescence spectra of Pr 3+ ions, we conclude that there are two unequivalent positions in LiPrP 4 O 12 crystals.

Investigations of the vibronic transitions in Cs2NaErCl6

Abstract The results of low temperature magnetic susceptibility measurements and infrared and Raman spectra have been used for the determination of the crystal field splitting of the low lying states of Er 3+ ions in Cs 2 NaErCl 6 single crystals, and for the calculation of the normal vibrations of the ErCl 3− 6 moiety. The low temperature optical absorption spectra were also measured and the obtained data have been used for the analysis of the vibronic transitions of Er 3+ ions. Assignments of the observed absorption bands have been proposed.

Investigation of emission spectra and lifetimes of Cs2NaErCl6 single crystals

Abstract The fluorescence spectra and lifetimes of low lying states of Er 3+ in Cs 2 NaErCl 6 single crystals have been investigated at room temperature and at 77 K. The assignments of the 4 F 9 2 - 4 I 15 2 and 4 I 11 2 - 4 I 15 2 phonon-assisted transitions have been proposed. The fluorescence lifetimes of low lying fluorescing levels have been estimated.

Spectroscopic investigations of neodymium-doped BaLaGa3O7 single crystals

Abstract Neodymium doped BaLaGa 3 O 7 obtained in single crystal form by the Czochralski method has been studied by both adsorption and emission spectroscopy. The experimental data have been used to determine the radiative transition probabilities, luminescence branching ratios and quantum efficiency of the luminescent state of Nd +3 .

Molecular design of new π-conjugated poly(ketanil)s with tunable spectroscopic properties

New conjugated aryl-substituted poly(azomethine)s, termed poly(ketanil)s, have been synthesised from 1,4-phenylenediamine (or 3,3′,5,5′-tetramethylbenzidine) and two different diketones via polycondensation with the goal to obtain new materials with tunable spectroscopic properties. It is demonstrated that both the absorption and photoluminescence spectra of these poly(ketanil)s can be modified not only by changing the chemical constitution of both repeating subunits in the polymer main chain but also via acid-base doping involving the protonation of the ketimine groups. By combining these two methods it is possible to precisely tune the absorption and emission spectra of the poly(ketanil)s. The use of bifunctional protonating agents, containing plasticising groups, for example 1,2-(di-2-ethylhexyl)ester of 4-sulfophthalic acid (DEHEPSA), in addition to modifying the spectroscopic properties of the polymers, leads to a lowering of their glass transition temperature (Tg), improving in such a manner the flexibility of the prepared poly(ketanil)s materials.

Investigation of infrared to visible conversion in Cs2Na(Er0.2Yb0.4Y0.4)Cl6 crystal

Abstract A conversion of infrared radiation into green fluorescence of Er +3 in centrosymmetric Cs 2 Na(Er 0.2 Yb 0.4 Y 0.4 )Cl 6 crystals is examined and interpreted on the basis of stepwise energy transfer mechanism. Some aspects of the conversion process are discussed.

Magnetic susceptibility and luminescence of α-ZnAl2S4 tiospinel doped with chromium

The magnetic susceptibility as well as the optical excitation and luminescence spectra of three samples of α-ZnAl2S4 tiospinel doped with Cr at various concentrations have been measured in the temperature range 77–300 K. The susceptibility has allowed us to estimate the concentration of Cr in the samples studied as lying in the range 0.01–0.06 at.%. Crystal-field theory, including spin–orbit coupling and the trigonal crystal field of the D3d site has been used to fit the optical data. The best-fit parameters of the tiospinel crystal are B20=4800, B40=32500, B43=−28500, F(2)=58800, F(4)=40500 and ξD=300 cm−1. The computational procedure used gives excellent agreement between the experimental and calculated energy levels of the Cr3+ ion in the α-ZnAl2S4 matrix.

Novel soluble aromatic poly(amideimide)s containing 9,9-diphenylfluorene moieties: characterization and optical properties

A series of aromatic poly(amideimide)s containing 9,9-diphenylfluorene moieties and the amide units in the main chain have been synthesized by solution polycondensation reaction of newly prepared diamidedianhydride with several aromatic diamines: 1,3-phenylenediamine, 3,3′-dimethoxy-biphenyl-4,4′-diamine, 4,4′-oxydianiline, 4,4′-(1,3-phenylenedioxy)dianiline, 4,4′-(9-fluorenylidene)dianiline and 1,5-diaminonaphthalene. Molecular structures of the polymers obtained have been characterized using 13C NMR, 1H NMR and FTIR spectroscopies. The polymers prepared are readily soluble in aprotic polar solvents, and form optically transparent films by solution casting. The resultant poly(amideimide)s have been analyzed by differential scanning calorimetry (DSC), thermogravimetry (TG) and wide-angle X-ray diffraction measurements. They exhibited high levels of thermal stability, with decomposition temperatures in the range 452–494 °C, and high glass transition temperatures (181–278 °C). The optical behavior of these polymers has been investigated in NMP solution as well as in the films. The photoluminescence (PL) spectra of the free-standing films prepared from the poly(amideimide)s exhibited maximum emission bands around 506–525 nm in the green region.

Luminescence properties of Pr3+ IN LiPrxLa1−xP4O12 crystals

Abstract The depopulation of excited state 3P0, 1D2 of the Pr3+ ions in LiPrxLa1−xP4O12 crystals was analyzed from luminescence measurements. The presented results indicate that in LiPrxLa1-xP4O12 system a strong luminescence quenching occurs, caused by the multiphonon relaxation of the excited states 3P1 and 3P0. The luminescence from the 1D2 level depends strongly on the concentration of Pr3+ ions.