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1

Photoinduced Charge-Transfer Reactions of Tricyanoethylene with Aromatic Hydrocarbon Electron Donors. II. Semiempirical Studies of Naphthalene-Tricyanoethylene Exciplex

100%

Deperasińska I., Prochorow J.

Acta Physica Polonica A

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2002

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vol. 102

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issue 6

811-826

EN

In this work we present the results of semiempirical AM1 calculations of the energy of electron-donor-acceptor system of naphthalene-tricyanoethylene complex in the ground and excited state with full optimization of the complex geometry. It was found that a ground state of the complex under consideration is stabilized almost exclusively by the electrostatic and Van der Waals interactions (presumably without charge-transfer resonance interaction). Its optimized equilibrium configuration has almost perpendicular head-to-face orientation of component molecules while in an excited state it is practically a charge-transfer electronic configuration with almost sandwich-like arrangement of both molecules. The energies of vertical electronic transitions between relevant ground and excited states and other spectroscopic parameters for these transitions were calculated with the use of ZINDO/S method and were compared with results of recent experimental observations of naphthalene-tricyanoethylene exciplex. This comparison led to a satisfactory explanation of the spectral properties and to a deeper insight into the kinetic parameters of the electron-donor-acceptor system under study.

2

Calculations of Cross Sections Data for Scattering of Electrons on HBr

100%

Radmilović-Radjenović M., Petrović Z.

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issue 5

745-747

EN

The R-matrix method provides a complete theoretical framework for the treatment of low energy electron collisions. The method has been implemented into code Quantemol-N (EE) with a goal to provide users in plasma modeling, swarm studies and other applications with an option to calculate the missing data. In this paper we report on cross sections and rate coefficients for hydrogen bromide obtained by using Quantemol-N. The total cross section has been calculated both with and without Born corrections.

3

Spectral and Time-Resolved Studies of Green Cs_{2} Fluorescence

100%

Bieniak B., Głódź M., Jastrzębski W., Szonert J.

Acta Physica Polonica A

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1993

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vol. 84

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issue 2

229-246

EN

The origin and dynamic properties of the green fluorescence of Cs_{2} excited by laser lines in the 457-488 nm range are studied. Emphasis is placed on the analysis of the 501-527 nrn range. The identified fluorescence line progressions are attributed to the E'(3)^{1}П_{u} → X^{1}∑^{+}_{g} transition. An extension of the attractive branch of the E'(3)^{1}П_{u} potential towards longer inter-nuclear distances is reconstructed by the semi-classical method. A narrow feature at 522 nm is found to be connected with a minimum of the difference potentiał. The lifetime values are measured. The multicomponent fluorescence decays are interpreted as evidence of perturbations of the E'(3)^{1}П_{u} state by a number of bound and repulsive states of dicherent symmetry. The predissociation rates are estimated.

4

Observing Quantum Level Interference Effects with Electron Spectrometer

100%

Özer Z., Ulu M., Aktaş B., Doğan M.

Acta Physica Polonica A

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2013

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vol. 123

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issue 2

363-364

EN

The existence of Young-type interference patterns has been recently searched in triple differential cross-sections for single ionization of H_2 molecules by electron impact, and theoretically supported by calculations obtained by different models. The appearance of interference effects arising from the two-centre geometry of diatomic molecule. These effects seen in triple differential cross-sections are described by interference factor in analogy with light waves. In this work, we discuss about that the interference factor for molecular structure of H_2 may reproduce Young-type interference patterns depending on scattering angle, initial and ejected electron energies in triple differential cross-sections. Differences are expected in the triple differential cross-sections spectra of ejected electrons according to kinematical conditions imposed by scattering angle and electron energy.

5

Cross Relaxation and Energy Transfer in Cs_{2}NaSm_{x}Eu_{y}Y_{1-x-y}Cl_{6}

80%

Luxbacher T., Fritzer H., Flint C.

Acta Physica Polonica A

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1996

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vol. 90

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issue 1

161-168

EN

Luminescence decay curves have been measured for the Sm^{3+} ^{4}G_{5/2} → ^{6}H_{7/2} emission in the cubic crystal Cs_{2}NaSm_{x}Eu_{y}Y_{1-x-y}Cl_{6} (x = 0.005 to x = 1, y = 0 to y = 0.99) over the temperature range 10 K to 300 K using pulsed laser excitation into the ^{4}G_{5/2} state of Sm^{3+}. The luminescence from the ^{4}G_{5/2} state of Sm^{3+} is strongly quenched by both, cross relaxation to nearest-neighbour Sm^{3+} ions and energy transfer to the ^{5}D_{0} state of Eu^{3+}. We interpret these processes in terms of a recently developed discrete shell model. The dependence of energy transfer from the Sm^{3+} donor ion to Eu^{3+} acceptor ions on y is readily studied and modelled. The temperature dependence shows that the cross relaxation occurs mainly by electric dipole vibronic-electric dipole vibronic interaction while in the energy-transfer process magnetic dipole allowed electronic contributions are also involved.

6

Theoretical Analysis of the Electronic Ground and Excited Franck-Condon State of 2-Alkylamino-(3, 5, or 6)-Methyl-4-Nitropyridine N-oxides

80%

Deperasińska I., Makarewicz A., Szemik-Hojniak A.

Acta Physica Polonica A

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2007

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vol. 112

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issue S

S-71-S-84

EN

We theoretically characterised properties of the electronic ground and excited Franck-Condon state of 2-alkylamino-(3, 5, or 6)-methyl-4- -nitropyridine N-oxides. The obtained results of time-dependent density functional theory calculations are consistent with the experimental absorption spectra. The nature of the lowest excited states of the considered N-oxides molecules is discussed. Two excited singlet states (in the midst of four lowest states) have the charge-transfer character. These states have different charge-transfer contribution of the two electron donor groups to the same electron acceptor. In consequence, different conditions for the promotion of intramolecular proton transfer in excited state are created in each case.

7

Advances in Fluorescence Spectroscopy: Multi-Photon Excitation, Engineered Proteins, Modulation Sensing and Microsecond Rhenium Metal-Ligand Complexes

80%

Lakowicz J., Gryczynski I., Tolosa L., Dattelbaum J., Castellano F., Li L., Rao G.

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vol. 95

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issue 1

179-196

EN

The technology and applications of fluorescence spectroscopy are rapidly advancing. In this overview presentation we summarize some recent developments from this laboratory. Two and three-photon excitation have been observed for a wide variety of intrinsic and extrinsic fluorophores, including tryptophan, tyrosine, DNA stains, membrane probes, and even alkanes. It has been possible to observe multi-photon excitation of biopolymers without obvious photochemical or photo-thermal effects. Although not described in our lecture, another area of increasing interest is the use of engineered proteins for chemical and clinical sensing. We show results for the glucose-galactose binding protein from E. coli. The labeled protein shows spectral changes in response to micromolar concentrations of glucose. This protein was used with a novel sensing method based on the modulated emission of the labeled proteins and a long lifetime reference fluorophore. And finally, we describe a recently developed rhenium complex which displays a lifetime near 3ľs in oxygenated aqueous solution. Such long lifetime probes allow detection of microsecond dynamic processes, bypassing the usual nanosecond timescale limit of fluorescence. The result of these developments in protein engineering, sensing methods, and metal-ligand probe chemistry will be the increased use of fluorescence in clinical chemistry and point-of-care analyses.

Refine search results

Photoinduced Charge-Transfer Reactions of Tricyanoethylene with Aromatic Hydrocarbon Electron Donors. II. Semiempirical Studies of Naphthalene-Tricyanoethylene Exciplex

Calculations of Cross Sections Data for Scattering of Electrons on HBr

Spectral and Time-Resolved Studies of Green Cs_{2} Fluorescence

Observing Quantum Level Interference Effects with Electron Spectrometer

Cross Relaxation and Energy Transfer in Cs_{2}NaSm_{x}Eu_{y}Y_{1-x-y}Cl_{6}

Theoretical Analysis of the Electronic Ground and Excited Franck-Condon State of 2-Alkylamino-(3, 5, or 6)-Methyl-4-Nitropyridine N-oxides

Advances in Fluorescence Spectroscopy: Multi-Photon Excitation, Engineered Proteins, Modulation Sensing and Microsecond Rhenium Metal-Ligand Complexes