Studies of opal crystals infiltrated with iron porphyrin

Synthetic opal crystals were infiltrated with concentrated (1–10 mM) aqueous solutions of iron porphyrin (FeTPPS). The assemblies of nanoscale blocks of 25–30 nm, which have been clustered into rod-like structures of size 100–150 nm typical of FeTPPS, were observed on the surface of silica spheres (diameter nm). Optical properties of infiltrated photonic crystals were investigated on the samples immersed into liquids. The absorption bands of FeTPPS were located in the vicinity of opal stop band, the position of which was tuned by varying the effective refractive index of opal immersed in various liquids. The absorption bands of FeTPPS were strongly influenced by ethanol presumably due to the formation of chemical bonds between sulfonic groups of FeTPPS with silanol groups on the surface of silica spheres and with ethoxy groups in ethanol environment. Data have shown that FeTPPS is a perspective material for the development of hybrid magnetophotonic devices based on the opal photonic crystalsPuslaidininkių fizikos institutasPuslaidininkių fizikos institutas, [email protected]ų fizikos institutas, [email protected] Didžiojo universitetasŠvietimo akademij

Structural features and superconductivity of Al-doped Y(RE)-123-type single crystals

The structure of a series of highly Al-doped superconducting Y(RE)-123 (RE = rare earth element) single crystals was investigated by XRD and NMR methods. On the basis of the data obtained by the structural investigations combined with the studies of magnetic and optical properties, the formation of various superstructures in the samples of pseudo-tetragonal symmetry has been discussed. The correlation between the carrier concentration and T-c-values has been determined. The superconductivity (at 70 K) was indicated even at the 2/3 and 1/3 Al substitution for Cu in the basal and CuO2 planes, respectively, in the phase presumably of a perovskite-like structural type

Poli(propileno-imino) dendrimerų UV spektrų savybės

Ištirti įvairių generacijų (G 1... GS) poli(propileno-imino) (PPI) dendrimerų, funkcionalizuotų aminogrupėmis, tirpalų dichlorometane sugerties spektrai. Nustatyta būdinga visiems ištirtiems junginiams dviguba juosta ties 270-290 nm ir jos kitimas priklausomai nuo dendrimerų generacijos ir tirpalo koncentracijos. Gauta, kad sugertis priklausė tiesiškai nuo dendrimero molinės koncentracijos tirpale, esant nedidelėms 1.10-5 M koncentracijoms. Aukštesnės generacijos (G3 ... GS) dendrimerų tirpalai pasižymėjo didele sklaida, kuri atitiko Rayleigh sklaidos dėsningumusThe UV optical spectra of amine terminated poly(propylene-imine) (PPI) dendrimers of generations G1 to G5 were investigated experimentally. The occurrence of double band at 270–290 nm in absorption spectra of amine terminated dendrimer and the dependence of the spectra on the generation number and concentration in dichloromethane solution were discussed. The lineshape of double band was similar in the sequence G1 to G5, though some redistribution of the intensity of components was observed. A linear dependence of the absorbance in the double band was determined in the solutions at low concentrations of order 1·10−5 M. Experimental data have indicated that double band is caused by several optical transitions related to the core electronic excitations. A significant Rayleigh light scattering was found for higher dendrimer generationsPuslaidininkių fizikos institutasVilniaus universiteto Teorinės fizikos ir astronomijos institutas, [email protected] Didžiojo universitetasŠvietimo akademij

Modification of photonic properties in porphyrin-infiltrated opal crystals

The obtained results have shown that using the designed procedure, opal crystals are efficient in retaining the solvents. This is in agreement with the results [15] obtained on sol–gel derived silica matrices impregnated with zinc-sulfonated porphyrins. The optical spectra of opal crystals infiltrated with FeTPPS underwent significant changes due to overlap of the stop band of opal crystals and absorption bands of FeTPPS. The provided experiments have demonstrated that the composite system of opal crystals infiltrated with FeTPPS can be considered as perspective material for magnetophotonic devices. In addition, the investigated hybrid samples can serve as a good model material for studying the optical effects due to overlapping of absorption bands of different origin in photonic crystalsPuslaidininkių fizikos institutasPuslaidininkių fizikos institutas, [email protected] Didžiojo universitetasŠvietimo akademij