Search results

1

Electronic Spectra of Salicylamide in Polycrystalline Form and Solid Environment

100%

Kakaš M., Janić I., Gúth I.

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vol. 95

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issue 2

199-205

EN

The fluorescence emission of crystalline salicylamide (λ_{max} = 426 nm, Stokes shift 6500 cm^{-1}) is attributed to the proton-transferred species. We suppose that the peak at 359 nm in the substructure of fluorescence excitation spectrum at 77 K is in fact the position of the 0-0 transition. The luminescence and excitation spectra of protolytic forms (anion, neutral molecule and cation) of salicylamide in solid solutions were also examined, as well as the equilibria and photoprocesses in the excited state.

2

Relaxation of Excited Eu(III) Complexes in Cetyltrimethylammonium Bromide Micellar Solutions

63%

Sennoga C., Flint C.

Acta Physica Polonica A

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1996

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vol. 90

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issue 2

327-332

EN

The equilibria between pyridine-2,6-dicarboxylate and Eu(III) in H_{2}O or D_{2}O cetyltrimethylammonium bromide micellar solutions at room temperature have been made as a function of the ligand concentration and pH by excitation spectroscopy and emission decay measurements. Formation of the tris-complex is complete at [Eu^{3+}]:[pdc^{2-}] ≥ 1:4 at neutral to slightly alkaline conditions but is incomplete under acidic conditions. The ^{5}D_{0} lifetimes corresponding to the Eu(pdc)_{3}^{3-} anion is observed to increase on association of the complex with the micellar surface due to exclusion of the solvating molecules from the second co-ordination sphere. Energy transfer in the bulk solution requires the presence of binuclear mixed Eu^{3+} and Nd(pdc)_{3}^{3-} complexes or confinement of the Ln(pdc)_{3}^{3-}/Eu^{3+} on the micelle surface. Energy transfer from the Eu(pdc)_{3}^{3-} anion is inefficient in the bulk solution.

3

Inductive-Resonant Theory of Nonradiative Transitions for Complex Organic Molecules in Condensed Phase

63%

Ermolaev V., Sveshnikova E.

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vol. 95

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issue 3

299-308

EN

Ours and literature data on influence of replacement of deuterium by protium in complex organic molecules on nonradiative triplet-singlet transition rates are discussed from the standpoint of the inductive-resonant theory of this process. It has been shown that the extent to which the protium introduction in molecule affects the nonradiative rate depends on distance between protium atom and the vibronic molecular oscillator of triplet-singlet transition and on π -electronic density near-by protium.

4

Fluorescence Properties of An Electron Acceptor Substituted Bis-Pyrazolo-Pyridine Derivative: NO_{2}-DMPP

63%

Rechthaler K., Schamschule R., Parusel A., Rotkiewicz K., Piorun D., Köhler G.

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vol. 95

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issue 3

321-334

EN

The fluorescence properties of 3,5-dimethyl-1,7-diphenyl-4 -(4'-nitro-phenyl)-bis-pyrazolo-[3,4-b;4',3'-e]-pyridine (NO_{2}-DMPP) and its parent compound 3,5-dimethyl-1,7-diphenyl-bis-pyrazolo-[3,4-b;4',3'-e]-pyridine (BPP, without the nitrophenyl substituent) were investigated. BPP is a highly fluorescent blue emitter and the fluorescence properties, the emission wavelength, and the fluorescence quantum yield, depend only slightly on solvent. On the contrary, acceptor substituted NO_{2}-DMPP shows dual fluorescence: A long-wavelength component experiences a red-shift with increasing solvent polarity but is efficiently quenched when the polarity exceeds that of solvents like 1,2-dichloroethane or 1-bromopropane. A weak short-wavelength component changes only slightly its position and intensity upon variation of the solvent but its yield increases strongly at low temperatures. The experimental results are discussed in the context of the results of semiempirical calculations which show that fluorescence originates from two closely lying fluorescent states which change their sequence and properties when the polarity of the solvent is varied. A twisted intramolecular charge transfer (TICT) state does most likely not contribute to the emission properties, because of its high energy.

5

Quasi-Molecule Model of the Spectra of Molecules in Polar Solution in Case of Time Dependent Fluorescence Shifts

63%

Bączyński A., Marszałek T., Radomska D., Targowski P., Ziętek B.

Acta Physica Polonica A

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1992

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vol. 82

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issue 3

413-420

EN

Analytical expressions of profiles of absorption and instantaneous fluorescence spectra of dye molecules in polar solvents are given. It is shown what parameters can be gained from electronic spectra of dye solutions. The new procedure of interpretation of transient fluorescence spectra is demonstrated in the case of the spectra of nile blue in alcohol.

6

Spectroscopy and Photophysics of Monoazaphenanthrenes III. Luminescence of Phenanthridine and 7,8-benzoquinoline in Crystalline State

63%

Norek M., Kozankiewicz B., Prochorow J.

Acta Physica Polonica A

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2004

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vol. 106

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issue 1

77-94

EN

Fluorescence and phosphorescence spectra and the decay profiles of both these emissions have been investigated for the polycrystals of phenanthridine and 7,8-benzoquinoline, in the liquid helium (5 K) - room temperature range. These two monoazaderivatives of phenanthrene, which differ only by the position of N-heteroatom in the aromatic ring skeleton of phenanthrene, were found to exhibit very different fluorescence spectra, which also differ greatly in their temperature behavior. Supplementary investigations of the fluorescence of single crystals of 7,8-benzoquinoline have supported classification of observed fluorescence as an excimer fluorescence (caused by the specific arrangement of molecules of 7,8-benzoquinoline in the crystal). In contrary fluorescence of phenanthridine crystals is of the monomeric type. Phosphorescence spectra observed for the crystals of both molecules are very similar, but their temperature dependence is also different. This may be considered as an indication of a different physical mechanism of nonradiative intersystem crossing processes, which are operating between the lowest excited singlet state and the lowest excited triplet state in the crystals of both molecules.

7

Terrylene in a 2,3-Dichloronaphthalene Crystal. New System for Optical Single-Molecule Investigations

63%

Białkowska M., Chaładaj W., Makarewicz A., Kozankiewicz B.

Acta Physica Polonica A

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2015

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vol. 128

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issue 3

RK.128.3.1-1-RK.128.3.1-4

EN

51%

Çelik G., Kurtuluş F.

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vol. 125

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issue 2

357-358

EN

CeVO_4 (ICDD: 12-757) was synthesized by microwave-assisted method by using cerium sulphate and vanadium (V) oxide in an appropriate molar ratio. Characterizations were done by X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet spectrophotometry and thermogravimetric/differential thermal analysis. The material is crystallized in tetragonal system with unit cell parameters a = 7.399 Å and c = 6.496 Å and space group I41/amd(141).

14

Measurement of Beet Root Extract Fluorescence Using TR-LIF Technique

51%

Rabasovic M., Sevic D., Terzic M., Savic-Sevic S., Muric B., Pantelic D., Marinkovic B.

Acta Physica Polonica A

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2009

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vol. 116

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issue 4

570-572

EN

Laser induced fluorescence is a powerful spectroscopic technique commonly used to study the structure and internal state distributions in molecules of biological interest. Betanin (C_{24}H_{26}N_{2}O_{13}) is a specific violet betacyanin and the most prominent pigment in the red beet root where it contributes to 75-95% of the total visible color. Our method of excitation of the beet root extract is based on the tunable (320 nm to 475 nm) Nd:YAG laser system. Fluorescence images of beet root extract excited at 320, 340, 360 and 400 nm were obtained. The fluorescence is observed in range from 580 nm to 660 nm. The influence of the solution concentrations on the fluorescence intensity is also analyzed.

15

Effects of Solute-Solvent Interactions on Radiationless Decay of Thioketones Excited to Their S_{2}- and T_{1}-States

51%

Szymański M., Balicki M., Binkowski M., Kubicki J., Maciejewski A., Pawłowska E., Wróżowa T.

Acta Physica Polonica A

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1996

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vol. 89

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issue 4

527-546

EN

Spectral and photophysical properties of a few aromatic thioketones in their S_{2}- and T_{1}-states, in particular those determined by their interactions with solvents, are discussed. The reasons for a drastically different behaviour of thioketones in interactions with benzene as well as saturated hydrocarbons and perfluoroalkanes are analysed in more detail. Results of the time-resolved transient absorption measurements in the pico- and nanosecond time scale are given. An analysis of these results proves that a product of the decay of the S_{2}-state of xanthione in benzene is a new transient (τ_{1/e} ≥ 60 ps) individuum which, regarding the system properties and the conditions of the experiment, has been identified as an exciplex in S_{2}-state formed as a result of an efficient interaction with benzene molecule. Also in xanthione//alkane systems the involvement of a transient individuum was proved. Most probably, this individuum was a thioketyl radical which could be formed by hydrogen abstraction from a hydrocarbon molecule by xanthione in the S_{2}-state. Such individua act as intermediates in passing excitation to the triplet states of thioketones and are effective channels of the S_{2}-state decay. The changes observed in the transient absorption spectra of xanthione in C_{6}H_{6} in the time range of 10^{-7}-10^{-6} s can be attributed to the formation of an excimer in the T_{1}-state as a result of the T_{1}-state selfquenching.

16

Spectroscopy of 2-aminopurine: An MCSCF Study

51%

Rachofsky E., Ross J., Krauss M., Osman R.

Acta Physica Polonica A

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1998

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vol. 94

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issue 5-6

735-748

EN

2-aminopurine is a highly fluorescent isomer of adenine that can be incorporated into DNA as a probe of structure, dynamics, and protein-DNA interactions. Interpretation of the fluorescence of 2-aminopurine in DNA requires a model of the electronic structure of this fluorophore in its ground and excited states. To this end, electronic structures and energies of the ground and lowest singlet excited states of 2-amino-9-methylpurine were calculated by the multiconfiguration self-consistent field method supplemented by multiconfiguration perturbation theory. The molecular geometry was optimized in both of these electronic states to permit investigation of both electronic excitation and fluorescence emission. The predicted energies and transition dipoles were in good agreement with experiment. The permanent molecular dipole of 2-amino-9-methylpurine increased upon excitation, suggesting that both the absorption and emission spectra should shift to slightly lower energies in polar solvents. The anomalous spectral shifts observed in water suggest that 2-aminopurine undergoes hydrogen bonding that better stabilizes the ground state than the excited state. From the calculated electrostatic potentials of these two states, the position at which this hydrogen bond forms was predicted. These results form a basis for understanding the excited states and possible intermolecular interactions of 2-aminopurine in DNA.

17

Electron-Phonon Coupling in Rare Earth Compounds

51%

Meijerink A., Blasse G., Sytsma J., de Mello Donega C., Ellens A.

Acta Physica Polonica A

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1996

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vol. 90

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issue 1

109-119

EN

The variation in electron-phonon coupling strength for rare earth ions has been studied by measuring vibronic transition probabilities and temperature dependent line broadening for a large number of rare earth ions in different host lattices. The results show a large variation in the electron-phonon coupling strength (almost three orders of magnitude) and a remarkable trend: the coupling is strong for ions in the beginning and at the end of the lanthanide series and weak in the middle. In covalent host lattices the coupling is much stronger than in ionic host lattices. An explanation of the results is given and the consequences of the variation of the electron-phonon coupling strength on phenomena like multiphonon relaxation, energy transfer and cooperative luminescence are discussed.

18

Comparative Study of Orientational Order of Some Liquid Crystals from Various Homologous Series

51%

Bielejewska N., Chrzumnicka E., Mykowska E., Przybylski R., Szybowicz M., Władysiak K., Bauman D.

Acta Physica Polonica A

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2006

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vol. 110

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issue 6

777-793

EN

The long-range orientational order of liquid crystals from homologous series of 4-n-alkyl-4'-cyanobiphenyl, 4-n-alkoxy-4'-cyanobiphenyl, trans-4-n-alkyl(4'-cyano-phenyl)-hexane, and 4-(trans-4'-n -alkylcyclohexyl)-isothiocyanato-benzene was studied by means of classical methods of optical spectroscopy: absorption of the polarized light, fluorescence depolarization, and Raman scattering depolarization. The absorption, emission, and Raman scattering spectra of linearly polarized light were recorded as a function of temperature in the whole range of the mesophase. On the basis of these spectra the order parameters ⟨P_2⟩ and ⟨P_4⟩ as well as the orientational distribution function were determined. The results obtained for members of various series with the same number of carbon atom in the alkyl chain were compared. It was found that the orientational order of liquid crystal molecules depends on the structure of the rigid core, on the kind of the terminal group as well as on the alkyl chain length. The odd-even effect for the order parameters, explained as the alteration of interaction between alkyl chains, was observed.

19

Spectroscopy and Photophysics of Monoazaphenanthrenes I. Absorption and Fluorescence Spectra of Phenanthridine and 7,8-Benzoquinoline

51%

Norek M., Dresner J., Prochorow J.

Acta Physica Polonica A

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2003

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vol. 104

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issue 5

425-439

EN

The absorption and fluorescence spectra of phenaentridine and 7,8-benzoquinoline have been measured in liquid solutions of non-polar, aprotic hydrocarbon solvents (n-hexane and cyclohexane) and in strongly polar (and hydrogen-bonding) methanol. The analysis of the Stokes' shift between absorption and fluorescence spectra has shown that for both molecules the observed solvent effects on their absorption and fluorescence spectra can be described in terms of universal solvent-solute interactions (no evidence of specific solvent-solute interactions, of the type of hydrogen bond formation with participation of lone-pair electrons of nitrogen atom, has been found). On the other hand, the measured decay time profiles of fluorescence are visibly longer in methanol solution than in non-polar, aprotic solvents and these observations are consistent with the observed increase in fluorescence intensity of both molecules in strongly polar methanol solution. The radiative lifetimes of the first excited singlet state do not differ noticeably for both molecules, but it has turned out that in the case of phenanthridine the nonradiative processes are getting less effective in methanol solution than in the case of 7,8-benzoquinoline, which can presumably be related to the role of different position of the substitution of nitrogen atom in these two molecules.

20

Spectroscopic Study of Rare Earth Chromates: Relation to the Structure

51%

Antic-Fidancev E., Lemaitre-Blaise M., Parada C.

Acta Physica Polonica A

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1996

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vol. 90

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issue 1

33-44

EN

The luminescence spectra of the trivalent europium ion embedded in various rare earth chromates were analyzed. The spectroscopic data in most of chromates are in agreement with the structural determination but for some others the discrepancy between two methods is underlined. Energy level schemes were deduced from the experimental emission spectra and the crystal field simulation has been performed. The maximum splitting of the ^{7}F_{1} manifold of the Eu^{3+} ion as a function of N_{v}, the so-called crystal field strength parameter, is given. This allows us to classify the compounds according to their crystal field extent.

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Electronic Spectra of Salicylamide in Polycrystalline Form and Solid Environment

Relaxation of Excited Eu(III) Complexes in Cetyltrimethylammonium Bromide Micellar Solutions

Inductive-Resonant Theory of Nonradiative Transitions for Complex Organic Molecules in Condensed Phase

Fluorescence Properties of An Electron Acceptor Substituted Bis-Pyrazolo-Pyridine Derivative: NO_{2}-DMPP

Quasi-Molecule Model of the Spectra of Molecules in Polar Solution in Case of Time Dependent Fluorescence Shifts

Spectroscopy and Photophysics of Monoazaphenanthrenes III. Luminescence of Phenanthridine and 7,8-benzoquinoline in Crystalline State

Terrylene in a 2,3-Dichloronaphthalene Crystal. New System for Optical Single-Molecule Investigations

From Jabłoński To Femtoseconds. Evolution of Molecular Photophysics

Analysis of Emission and Vibronic Transitions in Uranium(3+) Doped Cs_{2}LiYCl_{6} Single Crystals

Purely Electronic and Vibronic Fluorescence Excitation of Single Terrylene Molecules in a Naphthalene Crystal

Temperature Dependence of Luminescence Decay from the ^{4}G_{5/2} State of Sm^{3+} in Cs_{2}NaSm_{x}Y_{1-x}Cl_{6} and Cs_{2}NaSm_{x}Eu_{y}Y_{1-x-y}Cl_{6}

Optical Spectra of Neodymium and Europium Tungstates and Molybdates

Microwave-Assisted Synthesis of CeVO_4 in the Mild Conditions, Characterization and Investigation of Luminescent Properties

Measurement of Beet Root Extract Fluorescence Using TR-LIF Technique

Effects of Solute-Solvent Interactions on Radiationless Decay of Thioketones Excited to Their S_{2}- and T_{1}-States

Spectroscopy of 2-aminopurine: An MCSCF Study

Electron-Phonon Coupling in Rare Earth Compounds

Comparative Study of Orientational Order of Some Liquid Crystals from Various Homologous Series

Spectroscopy and Photophysics of Monoazaphenanthrenes I. Absorption and Fluorescence Spectra of Phenanthridine and 7,8-Benzoquinoline

Spectroscopic Study of Rare Earth Chromates: Relation to the Structure