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Wyświetlanie 1-15 z 89
Tytuł:
From Jabłoński To Femtoseconds. Evolution of Molecular Photophysics
Autorzy:
Kasha, M.
Powiązania:
https://bibliotekanauki.pl/articles/1993427.pdf
Data publikacji:
1999-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.50.-j
33.50.Dq
Opis:
A presentation is given, with retrospective commentary, on the experimental and theoretical contributions to key steps in the evolution of the framework of contemporary molecular photophysics from the Jablonski Diagram to femtosecond range excitation phenomena. The distinctive features of polyatomic molecules separating their behavior from atomic and diatomic molecules are emphasized. Justification is given for the statement that spin-orbital coupling with its relativistic component commonly dominates the molecular excitation dynamics of light-(low-Z)-atom molecules. The paper deals with single-photon, single-molecule excitations. Some examples of single-photon, multi-molecule and multi-photon, single-molecule excitation phenomena are listed. A selection of these is made to illustrate the prevalence of femtosecond excitation modes.
Źródło:
Acta Physica Polonica A; 1999, 95, 1; 15-36
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron-Phonon Coupling in Rare Earth Compounds
Autorzy:
Meijerink, A.
Blasse, G.
Sytsma, J.
de Mello Donega, C.
Ellens, A.
Powiązania:
https://bibliotekanauki.pl/articles/1945477.pdf
Data publikacji:
1996-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.70.Jg
33.50.Dq
33.50.Hv
Opis:
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.
Źródło:
Acta Physica Polonica A; 1996, 90, 1; 109-119
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Solute-Solvent Interactions on Radiationless Decay of Thioketones Excited to Their S$\text{}_{2}$- and T$\text{}_{1}$-States
Autorzy:
Szymański, M.
Balicki, M.
Binkowski, M.
Kubicki, J.
Maciejewski, A.
Pawłowska, E.
Wróżowa, T.
Powiązania:
https://bibliotekanauki.pl/articles/1945389.pdf
Data publikacji:
1996-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.50.Dq
33.50.Hv
35.80.Be
Opis:
Spectral and photophysical properties of a few aromatic thioketones in their S$\text{}_{2}$- and T$\text{}_{1}$-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$\text{}_{2}$-state of xanthione in benzene is a new transient (τ $\text{}_{1}\text{}_{/}\text{}_{e}$ ≥ 60 ps) individuum which, regarding the system properties and the conditions of the experiment, has been identified as an exciplex in S$\text{}_{2}$-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$\text{}_{2}$-state. Such individua act as intermediates in passing excitation to the triplet states of thioketones and are effective channels of the S$\text{}_{2}$-state decay. The changes observed in the transient absorption spectra of xanthione in C$\text{}_{6}$H$\text{}_{6}$ in the time range of 10$\text{}^{-7}$-10$\text{}^{-6}$ s can be attributed to the formation of an excimer in the T$\text{}_{1}$-state as a result of the T$\text{}_{1}$-state selfquenching.
Źródło:
Acta Physica Polonica A; 1996, 89, 4; 527-546
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature Dependence of Luminescence Decay from the $\text{}^{4}$G $\text{}_{5}\text{}_{/}\text{}_{2}$ State of Sm$\text{}^{3+}$ in Cs$\text{}_{2}$NaSm$\text{}_{x}$Y$\text{}_{1-x}$Cl$\text{}_{6}$ and Cs$\text{}_{2}$NaSm$\text{}_{x}$Eu$\text{}_{y}$Y$\text{}_{1-x-y}$Cl$\text{}_{6}$
Autorzy:
Luxbacher, T.
Fritzer, H. P.
Flint, C. D.
Powiązania:
https://bibliotekanauki.pl/articles/1945619.pdf
Data publikacji:
1996-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.50.Dq
33.50.Hv
78.55.Hx
Opis:
Luminescence decay curves for the $\text{}^{4}$G $\text{}_{5}\text{}_{/}\text{}_{2}$ → $\text{}^{6}$H $\text{}_{7}\text{}_{/}\text{}_{2}$ emission of Sm$\text{}^{3+}$ in the cubic hexachloroelpasolite crystals Cs$\text{}_{2}$NaSm$\text{}_{x}$Y$\text{}_{1-x}$Cl$\text{}_{6}$ (x=0.005 to x=1) and Cs$\text{}_{2}$NaSm$\text{}_{x}$Eu$\text{}_{y}$Y$\text{}_{1-x-y}$Cl$\text{}_{6}$ (x=0.01 to x=0.95, y=0.05 to y =0.99) have been measured over the temperature range 10 K to 300 K using pulsed laser excitation into the $\text{}^{4}$G $\text{}_{5}\text{}_{/}\text{}_{2}$ state of Sm$\text{}^{3+}$. The luminescence from this state is strongly quenched by cross relaxation to Sm$\text{}^{3+}$ acceptors and energy transfer to the $\text{}^{5}$D$\text{}_{0}$ state of Eu$\text{}^{3+}$. The temperature dependence of cross relaxation and of energy transfer is discussed in terms of the involved mechanisms.
Źródło:
Acta Physica Polonica A; 1996, 90, 2; 307-313
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Spectra of Salicylamide in Polycrystalline Form and Solid Environment
Autorzy:
Kakaš, M.
Janić, I.
Gúth, I.
Powiązania:
https://bibliotekanauki.pl/articles/1994577.pdf
Data publikacji:
1999-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.50.Dq
Opis:
The fluorescence emission of crystalline salicylamide (λ$\text{}_{max}$ = 426 nm, Stokes shift 6500 cm$\text{}^{-1}$) 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.
Źródło:
Acta Physica Polonica A; 1999, 95, 2; 199-205
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Emission Spectra of Triple Activated SrS Phosphors
Autorzy:
Rao, A. P.
Sinha, O. P.
Machwe, V. G.
Mehta, A. S.
Powiązania:
https://bibliotekanauki.pl/articles/1945381.pdf
Data publikacji:
1996-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.50.-j
Opis:
Fluorescence spectra of strontium sulphide phosphors activated by three activators viz. Mn, Cu, and Gd individually and in different combinations have been discussed at length. X-ray is used as excitation source. Probable inferences are drawn regarding energy transfer phenomenon. The two channels for transfer of energy are concluded in present phosphor series. A model is also proposed.
Źródło:
Acta Physica Polonica A; 1996, 89, 4; 509-516
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Empirical L Shell Fluorescence Yields for Elements with 40 ≤ Z ≤ 92
Autorzy:
Bendjedi, A.
Deghfel, B.
Derradj, I.
Kahoul, A.
Khalfallah, F.
Sahnoune, Y.
Bentabet, A.
Nekkab, M.
Powiązania:
https://bibliotekanauki.pl/articles/1030357.pdf
Data publikacji:
2017-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.50.-j
Opis:
Based on the fact that ratio of ionization to X-ray production cross-sections are independent of the excitation energy of projectile for a given target, we have deduced a new values of L shell average fluorescence yield from existing experimental compilation (till 2014) for a wide range of elements (40 ≤ Z ≤ 92) by proton impact (up to 10.0 MeV) of ionization and X-ray production cross-sections which are found to be universal when plotted as a function of the scaled velocity of projectile. The obtained empirical cross-sections are found reliable and then exploited to derive new values of average fluorescence yield. The obtained values are compared with earlier theoretical and experimental results and an agreement is observed for all elements.
Źródło:
Acta Physica Polonica A; 2017, 131, 1; 13-15
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fluorescence Decay Heterogeneity Model Based on Electron Transfer Processes in an Enzyme-Ligand Complex
Autorzy:
Wlodarczyk, J.
Kierdaszuk, B.
Powiązania:
https://bibliotekanauki.pl/articles/2043367.pdf
Data publikacji:
2005-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.50.-j
Opis:
The models are described for complex fluorescence decay of tyrosine in proteins involving continuous distribution of fluorescence lifetimes and electron transfer processes. We introduce the analytical decay function with a power-like term, which provides good fits to highly complex fluorescence decays. Moreover, the power-like term in the proposed decay functions is a manifestation of so-called Tsallis nonextensive statistics and is suitable for description of the systems with long-range interactions, memory effect, as well as with fluctuations of the characteristic lifetime of fluorescence. The proposed decay functions were applied to analysis of fluorescence decays of tyrosine in a protein, i.e. the enzyme purine nucleoside phosphorylase from E. coli, free in aqueous solution and in the complex with formycin A (an inhibitor) and orthophosphate (a co-substrate), and demonstrated that both models reflect the enzyme-ligand interactions. Direct measure of heterogeneity of the enzyme systems is provided by a variance of fluorescence lifetime distribution. The possible number of deactivation channels and excited state mean lifetime can be easily derived without a priori knowledge of the complexity of studied system.
Źródło:
Acta Physica Polonica A; 2005, 107, 6; 883-894
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anisotropic Fluorescence of Polar Molecules in External Electric Field, Dipole Moments of Para-Disubstituted Transstilbenes in the First Excited Singlet State
Autorzy:
Kawski, A.
Kubicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/1887289.pdf
Data publikacji:
1991-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.50.-j
Opis:
The electric dipole moments μ$\text{}_{e}$ in the lowest excited singlet state of nine short-lived para-disubstituted trans-stilbenes were determined experimentally based on the effect of the external electric field on the fluorescence anisotropy. The values of μ$\text{}_{e}$ obtained from Liptay's theory with the employment of the Onsager effective field are in satisfactory agreement with those calculated based on the solvatochromic effect. In the case of para-substituted trans-stilbenes with the same donor substituent R = N(CH$\text{}_{3}$)$\text{}_{2}$ in position 4 and different acceptors R' in position 4', the enhancing electron properties of the acceptor are accompanied by the increase in μ$\text{}_{g}$ - the dipole moment in the ground state, and μ$\text{}_{e}$ - the dipole moment in the excited state. There exists a linear relation between the values of μ$\text{}_{e}$ and μ$\text{}_{g}$.
Źródło:
Acta Physica Polonica A; 1991, 79, 4; 457-470
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spectroscopic Study of Rare Earth Chromates: Relation to the Structure
Autorzy:
Antic-Fidancev, E.
Lemaitre-Blaise, M.
Parada, C.
Powiązania:
https://bibliotekanauki.pl/articles/1945460.pdf
Data publikacji:
1996-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.50.Dq
33.50.Hv
71.70.Ch
78.50.Ec
Opis:
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 $\text{}^{7}$F$\text{}_{1}$ manifold of the Eu$\text{}^{3+}$ ion as a function of N$\text{}_{v}$, the so-called crystal field strength parameter, is given. This allows us to classify the compounds according to their crystal field extent.
Źródło:
Acta Physica Polonica A; 1996, 90, 1; 33-44
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural Aspects of Photochromism of the Internally H-Bonded Schiff Bases. "A Minimal Chromophore"
Autorzy:
Grabowska, A.
Kownacki, K.
Kaczmarek, Ł.
Powiązania:
https://bibliotekanauki.pl/articles/1943895.pdf
Data publikacji:
1995-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.10.-n
33.50.-j
Opis:
The final limiting stage of structural simplification of photochromic Schiff base was reached by the following statement: two molecules, salicylidene methylamine and its butyl analogue, show transient absorption bands (at room temperature) peaking at ≈ 22000 cm$\text{}^{-1}$. These bands are characteristic of the phenomenon of photochromism. They are similar to the corresponding spectra detected earlier for several larger, symmetric systems belonging to the same family. Experimental characterization of both molecules was compared with the theoretical calculations: geometry optimization and transition energies, performed for enol, keto, and the photochromic form of salicylidene methylamine.
Źródło:
Acta Physica Polonica A; 1995, 88, 6; 1081-1088
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Intramolecular Charge Transfer with N,N-Dialkyl-4-(Trifluoromethyl)anilines and 4-(Dimethylamino)benzonitrile in Polar Solvents. Investigation of the Excitation Wavelength Dependence of the Reaction Pathway
Autorzy:
Galievsky, V.
Zachariasse, K.
Powiązania:
https://bibliotekanauki.pl/articles/1813985.pdf
Data publikacji:
2007-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.20.-t
33.50.-j
Opis:
In the series of N,N-di-n-alkyl-4-(trifluoromethyl)anilines (DXCF3), with X = M (methyl), E (ethyl), Pr (n-propyl) and Pe (n-pentyl), an intramolecular charge transfer (ICT) reaction takes place in the polar solvent acetonitrile (MeCN). Such a reaction does not occur in the less polar solvents $n$-hexane and diethyl ether, in which a single fluorescence band from the locally excited (LE) state is observed. For DMCF3 in MeCN at 25ºC, the intramolecular charge transfer reaction efficiency is much smaller than for 4-(dimethylamino)benzonitrile (DMABN) in this solvent, as seen from the ICT/LE fluorescence quantum yield ratio Φ'(ICT)/Φ(LE): 0.06 for DMCF3 and 39.5 for DMABN. As predicted by the planar ICT (PICT) model, this difference is caused by the considerably larger energy gap Δ E($S_1$,S_2) of DMCF3 (5750 $cm^{-1}$) as compared with that of DMABN (3130 $cm^{-1}$). When the alkyl chain length of DXCF3 becomes larger, Φ'(ICT)/Φ(LE) in MeCN at 25ºC increases, from 0.06 for DMCF3 to 0.64 for DPeCF3. This increase in ICT reaction efficiency is accompanied by a small but significant decrease of 380 $cm^{-1}$ for Δ E($S_1$,S_2) when going from DMCF3 to DPeCF3. Because of their relatively large Δ E($S_1$,S_2) gap, the molecules DXCF3 are suitable for an investigation of the excitation wavelength dependence of the intramolecular charge transfer reaction. For DPrCF3 in MeCN, the same Φ'(ICT)/Φ(LE) is found for excitation in the $S_1$ or in the $S_2$ manifold. A similar result is obtained with DMABN in tetrahydrofuran. From these experiments it is concluded that for DPrCF3 and DMABN the intramolecular charge transfer reaction follows an adiabatic pathway. After excitation to a Franck-Condon $S_n(FC)$ state, the electron donor/acceptor molecules first undergo ultrafast internal conversion to the relaxed $LE(S_1)$ state, from which precursor the reaction proceeds to the ICT state. Experimental evidence for a nonadiabatic ICT reaction pathway, going directly from $S_2(FC)$ via an $S_2//S_1$ conical intersection to the LE and ICT state, is not found. This pathway would lead to an enhancement of the ICT population, i.e., to an increase in Φ'(ICT)/Φ(LE), as compared with the adiabatic LE → ICT reaction.
Źródło:
Acta Physica Polonica A; 2007, 112, S; S-39-S-56
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin-Allowed Vibronic Transitions in Molecules: Radiative and Non-Radiative Transition Moments by Including Static and Vibronic Spin-Orbit Coupling within the Adiabatic Approximation
Autorzy:
Gustav, K.
Powiązania:
https://bibliotekanauki.pl/articles/1891927.pdf
Data publikacji:
1991-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.50.-j
82.50.-m
Opis:
By making use of the second order Herzberg-Teller approach within the adiabatic approximation including the static and vibronic spin-orbit coupling the vibronic transition moments for spin-allowed radiative and non-radiative processes are derived. The role and the contribution of spin-orbit coupling to both transition moments are illustrated.
Źródło:
Acta Physica Polonica A; 1991, 80, 6; 793-800
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Emission of Acridine and its Aggregates Isolated in the Neon Matrix
Autorzy:
Prochorow, J.
Kozankiewicz, B.
Dongo Gemi, Bango Bango
Morawski, O.
Powiązania:
https://bibliotekanauki.pl/articles/1992729.pdf
Data publikacji:
1998-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
31.50.+w
33.50.-j
Opis:
The results of experimental studies of fluorescence and phosphorescence of acridine in the low-temperature inert neon matrix, at 7 K, are reported. It is found that the low-temperature inert matrix of neon affects the energy levels of acridine molecules very weakly even as compared with nonpolar (aprotic) and non-reactive solvent (e.g. hexane) and that there are different sites for acridine molecules in the neon matrix. However, the observed fluorescence spectra are strongly dependent on the excitation wavelength and besides the different (monomer) sites other emitting species are also contributing to the observed fluorescence emission of acridine in the neon matrix. Clear-cut evidence of the formation of singlet excimers of acridine in the neon matrix demonstrates itself as a very broad and structureless fluorescence spectrum with a relatively large shift from the origin of monomer (site) fluorescence which is characterized by a very distinct vibrational structure. The phosphorescence emission was observed only for the monomers. The observed differences in the low-energy part of excitation spectra of phosphorescence and fluorescence are discussed in terms of the close-lying excited singlet states of n,π* and π,π* character (mixed by the vibronic coupling) and tentatively interpreted as due to the formation of resonance acridine dimers. Their fluorescence spectrum is slightly shifted toward lower energies from the origin of monomer (site) fluorescence.
Źródło:
Acta Physica Polonica A; 1998, 94, 5-6; 749-760
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Purely Electronic and Vibronic Fluorescence Excitation of Single Terrylene Molecules in a Naphthalene Crystal
Autorzy:
Banasiewicz, M.
Dresner, J.
Morawski, O.
Wiącek, D.
Kozankiewicz, B.
Powiązania:
https://bibliotekanauki.pl/articles/1814019.pdf
Data publikacji:
2007-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
32.50.+d
33.20.Kf
33.50.Dq
Opis:
Fluorescence excitation spectra of spatially resolved single terrylene molecules in a naphthalene crystal were studied at 5 K as a function of exciting laser light intensity. The fully saturated fluorescence detection rate for purely electronic transition (0,0) was found to be about twice smaller than that for the two main vibronic components located 239 and 251 $cm^{-1}$ above. This relation is fulfilled when the triplet population rate $k_{23}$ is much weaker than the depopulation rate $k_{31}$. We propose that the weak fluorescence excitation lines observed at the frequencies of 38, 67, 97, and 145 $cm^{-1}$ correspond to nontotally symmetric low-frequency vibration modes of terrylene.
Źródło:
Acta Physica Polonica A; 2007, 112, S; S-85-S-94
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 89

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