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Your search keyword '"Polosan, S."' showing total 126 results
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126 results on '"Polosan, S."'

2. Mud and burnt Roman bricks from Romula

Author

Badica, P., Alexandru-Dinu, A., Grigoroscuta, M. A., Burdusel, M., Aldica, G. V., Sandu, V., Bartha, C., Polosan, S., Galatanu, A., Kuncser, V., Enculescu, M., Locovei, C., Porosnicu, I., Tiseanu, I., Ferbinteanu, M., Savulescu, I., Negru, M., and Batalu, N. D.

Published
2022
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30. Mechanisms of the Charge Transfer in IrQ(ppy)2–5Cl Dual-Emitter Compound

Author

Polosan S and Radu Ic

Subjects
education.field_of_study, Materials science, Ligand, Quinoline, Population, Biomedical Engineering, Bioengineering, General Chemistry, Condensed Matter Physics, Photochemistry, Delocalized electron, chemistry.chemical_compound, chemistry, General Materials Science, Molecular orbital, Density functional theory, Singlet state, Phosphorescence, education
Abstract

The synthesis of IrQ(ppy)2-5Cl has the advantage of a dual phosphorescence (green and red) which comes from the two ligands, phenylpyridine and quinoline. Their spectroscopic properties evidences the absorption range between 350 nm to 700 nm which is composed from the singlet and triplet states, as a result of hybridizations between Ir and the two ligands, the first one being at 625 nm. The first low energy state comes from the quinoline ligand and is responsible for the red phosphorescence at 660 nm, as results from the Density Functional Theory (DFT) analysis. The hybridization between Ir 5d orbitals and pi ligand orbitals shows strong metallic character with phenylpyridine orbitals (66% and 43%) and weak metallic character with quinoline ligand (16.8%). This fact suggests weak phosphorescence intensity in the emission spectra. Population analysis of each metallic orbital shows a small charge delocalization on the quinoline ligand for the first molecular orbital and a strong delocalization on the phenylpyridine ligands. Solvation effects induce a tuning process for the phosphorescence by changing of the matrix of the organometallic compounds which can be adjusted by the strength of intermolecular dipole-dipole interactions, using a doped guest-host molecular organic thin film system.

Published
2013

32. Radiation Induced Defects in Pb2+-Doped LiF Crystals

Author

Somma, F., Montereali, R.M., Vincenti, M.A., Polosan, S., Secu, M., Somma, Fabrizia, R. M., Montereali, M. A., Vincenti, S., Polosan, M., Secu, MONTEREALI R., M, VINCENTI M., A, Polosan, S, and F., Somma

Subjects
LiF crystal, genetic structures, Optical absorption, Radiation defects, Photoluminescence
Abstract

The influence of Pb2+ doping on the optical properties of LiF crystals before and after irradiation with X-ray was studied by using optical absorption and photoluminescence measurements. After irradiation it was observed an increase of the absorption due to primary and aggregate electronic defects together with a higher photoluminescence signals associated with the F2 and F3+ colour centres in doped samples compared with the undoped ones.

Published
2010

50. Dual emitter IrQ(ppy)2 for OLED applications: Synthesis and spectroscopic analysis.

Author

Ciobotaru, I.C., Polosan, S., and Ciobotaru, C.C.

Subjects
*ORGANIC light-emitting diode televisions, *SPECTRUM analysis, *ORGANIC synthesis, *ORGANOMETALLIC compounds, *DICHLOROMETHANE, *PHOTOLUMINESCENCE, *CATHODOLUMINESCENCE
Abstract

Abstract: The synthesis of organometallic compound with iridium and two types of ligands, quinoline and phenylpyridine, was done successfully. The absorption spectra of this compound have shown broad peaks in a visible region assigned to metal-to-ligands charge transfer and in UV region assigned to intraligand absorptions. The photoluminescence spectra exhibit dual character in which the red emission is more intense than the green one. In cathodoluminescence measurements, under electron beam, the powder obtained after recrystallization from dichloromethane, shows similar behaviors with photoluminescence spectra. The cathodoluminescence images have shown a luminescent crystalline powder with triclinic structure. This compound exhibits combined vibrational modes, which proves the presence in the same molecule of both ligands. Density Functional Theory calculation was involved in order to identify the main vibrations of this compound. [Copyright &y& Elsevier]

Published
2014
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