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Wyszukujesz frazę "T30" wg kryterium: Temat


Tytuł:
1,1-Dithiolenes: the Good, the Not Bad, and the Ugly
Autorzy:
Cassoux, P.
Bowlas, C. J.
Lahlil, K.
Moradpour, A.
Bonvoisin, J.
Launay, J.-P
Powiązania:
https://bibliotekanauki.pl/articles/1933327.pdf
Data publikacji:
1995-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.20.-t
82.40.-g
82.45.+z
33.10.-n
82.30.-b
Opis:
A series of 1, 1'-dithiolate ligands were used in the attempted preparation of metal complexes. These bidentate sulphur ligands were subsequently used in aromatic nucleophilic substitution reactions giving rise to several novel organic donor molecules. The electrochemistry data of two of the donors and their subsequent use in the preparation of donor-acceptor compounds is presented. One donor-acceptor compound exhibited high room temperature conductivity (up to 900 S cm$\text{}^{-1}$) and remained metallic down to low temperature. One donor containing two tetrathiafulvalene units was studied by near infrared absorption spectroscopy. An intervalence transition in the monocation form of this donor was observed, indicating that it behaves as a class II mixed valence compound.
Źródło:
Acta Physica Polonica A; 1995, 87, 4-5; 743-748
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Deformation of a Spherical Molecule
Autorzy:
Apostol, M.
Powiązania:
https://bibliotekanauki.pl/articles/1933570.pdf
Data publikacji:
1995-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.20.-t
61.46.+w
46.30.-i
Opis:
The deformation suffered by a hollow, spherical molecule as an effect of rotations is studied within a continuum model which might be relevant for the fullerene molecule. The spherical elasticity is established to the lowest order in deformations and the natural perturbation parameter required by the stability of the object is identified as the square ratio of the rotation to the radial vibration pulsations. It is also shown that the main effect of the centrifugal coupling between rotations and radial vibrations is a static deformation whose energy is beyond the harmonic approximation.
Źródło:
Acta Physica Polonica A; 1995, 88, 2; 315-325
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High Pressure - High Temperature Diffraction Study of MnTe Using Synchrotron Radiation
Autorzy:
Paszkowicz, W.
Dynowska, E.
Peun, T.
Powiązania:
https://bibliotekanauki.pl/articles/1964125.pdf
Data publikacji:
1997-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.30.+t
62.50.+p
65.70.+y
Opis:
High pressure - high temperature experiments for MnTe of NiAs type were performed using a synchrotron radiation as X-ray source and a cubic anvil X-ray diffraction press to produce nonambient sample environment. In the investigated range of pressure (0-67.5 kbar) on uploading and with following temperature rise from 296 to 1273 K (at 67.5 kbar), the structure type of MnTe is conserved. An earlier reported nonlinear behaviour of lattice-parameter c$\text{}_{0}$ is not found in the present study. Possible reasons of this discrepancy are discussed. The value of bulk modulus and its pressure derivative were calculated from the pressure-volume dependence by fitting the Birch-Murnaghan equation.
Źródło:
Acta Physica Polonica A; 1997, 91, 5; 939-944
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-Pressure Diffraction Study of Ga$\text{}_{1-x}$Al$\text{}_{x}$As
Autorzy:
Paszkowicz, W.
Dynowska, E.
Żytkiewicz, Z. R.
Dobosz, D.
Otto, J. W.
Powiązania:
https://bibliotekanauki.pl/articles/1964159.pdf
Data publikacji:
1997-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.30.+t
62.50.+p
64.70.Kw
Opis:
The Ga$\text{}_{1-x}$Al$\text{}_{x}$As sample of x=0.5 was prepared from a high quality single crystal grown by electroepitaxy on GaAs. The high-pressure diffraction experiments were performed using a diamond anvil cell and a germanium solid state detector. The zinc-blende phase is stable up to about 17.5 GPa on uploading. A high-pressure phase manifests itself at about 17 GPa, a complete phase change occurs at 18.7 GPa. On downloading, the zinc-blende phase reappears at about 10 GPa. The powder pattern of the high-pressure phase shows some similarities with the GaAs high pressure phases.
Źródło:
Acta Physica Polonica A; 1997, 91, 5; 993-996
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Alloying Effect on K X-Ray Fluorescence Cross-Section in Cr$\text{}_{x}$Ni$\text{}_{1-x}$ and Cr$\text{}_{x}$Al$\text{}_{1-x}$ Alloys
Autorzy:
Büyükkasap, E.
Powiązania:
https://bibliotekanauki.pl/articles/1968903.pdf
Data publikacji:
1998-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
32.30.-r
32.80.-t
Opis:
Alloying effect on the K$\text{}_{α}$ and K$\text{}_{β}$ X-ray fluorescence cross-sections in Cr$\text{}_{x}$Ni$\text{}_{1-x}$ and Cr$\text{}_{x}$Al$\text{}_{1-x}$ alloys was studied. The samples were excited by gamma rays with energy 59.5 keV from a$\text{}^{241}$Am radioisotope source and K X-rays emitted by the samples were counted with a Si(Li) detector. We found that K$\text{}_{α}$ and K$\text{}_{β}$ X-ray fluorescence cross-sections are changed by alloying effect in Cr$\text{}_{x}$Ni$\text{}_{1-x}$ and Cr$\text{}_{x}$Al$\text{}_{1-x}$ alloys for different composition x. We compared our results with the theoretical values.
Źródło:
Acta Physica Polonica A; 1998, 93, 5-6; 701-705
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photoinduced Electron Transfer in Jet Cooled Molecular Complexes
Autorzy:
Piuzzi, F.
Uridat, D.
Dimicoli, I.
Mons, M.
Tramer, A.
LeBarbu, K.
Lahmani, F.
Zehnacker-Rentien, A.
Powiązania:
https://bibliotekanauki.pl/articles/1994237.pdf
Data publikacji:
1999-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
31.50.+w
32.30.-r
33.15.-e
33.20.-t
Opis:
Exciplex and excimer formation have been probed in several jet cooled complexes using mass selective two-photon ionisation and fluorescence excitation spectroscopy as well as ground state depletion spectroscopy (hole burning): (i) In the anthracene-dimethyl-ortho-toluidine system, it has been found that the ionisation step takes place with a much higher efficiency from the charge transfer state responsible for the exciplex emission than from the locally excited state giving rise to the resonant fluorescence. (ii) The dimer, trimer, and higher clusters of anthracene all show only excimer emission. When compared to the dimer, the trimer exhibits a peculiar behaviour (structured fluorescence excitation and hole burning spectra, short lifetime and low ionisation efficiency) which has been related to a significant locally excited character of the initially prepared state of the species excited state. (iii) The influence of an intermolecular hydrogen bond on the electron transfer process has been studied in the 2,2,2-trifluoro-1-(9-anthryl)ethanol- dimethylaniline system. A threshold for exciplex formation higher than in the case of the anthracene-dimethylaniline complex is observed.
Źródło:
Acta Physica Polonica A; 1999, 95, 1; 121-135
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Restricted Validity of the Two-State Model Describing a Vibronic EPR g-Factors Averaging in Cs$\text{}_{2}$Zn(SO$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$O Tutton Salt Crystals Doped with Cu$\text{}^{2+}$ Ions
Autorzy:
Hoffmann, S. K.
Kaszyński, R.
Augustyniak, M. A.
Hilczer, W.
Powiązania:
https://bibliotekanauki.pl/articles/2011161.pdf
Data publikacji:
1999-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.90.+t
76.30.-v
Opis:
Single crystals and powder EPR spectra of Cu$\text{}^{2+}$ ions in Cs$\text{}_{2}$Zn(SO$\text{}_{4}$)$\text{}_{6}$·6H$\text{}_{2}$O were recorded in the temperature range of 4.2-300 K and the g-factor temperature variations were determined. The g$\text{}_{z}$ and g$\text{}_{y}$ have the values of 2.443 and 2.134, respectively, at the rigid lattice limit below 20 K, and then continuously tend to an average value on heating. This vibronic averaging produced by reorientations of Cu(H$\text{}_{2}$O)$\text{}_{6}$-complexes between Jahn-Teller distorted octahedral configurations is described in terms of a two-state Silver-Getz model which is known as a good model for diamagnetic non-ammonium Tutton salts. We found, however, that this model is only a crude approximation in Cs$\text{}_{2}$Zn(SO$\text{}_{4}$)$\text{}_{6}$·6H$\text{}_{2}$O below 150 K. Above this temperature the model works better and describes the vibronic dynamics between the two lowest energy potential wells in the adiabatic potential surface differing in the energy of δ$\text{}_{12}$=318(9) cm$\text{}^{-1}$=3.7 kJ/mol.
Źródło:
Acta Physica Polonica A; 1999, 96, 6; 733-740
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Resistance and Phase Transitions Studies for Some composite Materials Based on Al$\text{}_{2}$O$\text{}_{3}$
Autorzy:
Górski, L.
Powiązania:
https://bibliotekanauki.pl/articles/2011028.pdf
Data publikacji:
1999-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.50.Ks
81.30.-t
Opis:
In this paper the studies of phase transitions in some material compositions based on Al$\text{}_{2}$O$\text{}_{3}$ caused by high-temperature processes are presented. These material compositions may be used to high-temperature resistant plasma sprayed coatings. The occurring phase transitions are studied by X-ray diffraction methods. Phase transitions and thermal resistance for studied oxide systems are different. In the coatings from the materials belonging to Al$\text{}_{2}$O$\text{}_{3}$-NiO and Al$\text{}_{2}$O$\text{}_{3}$- ZrO$\text{}_{2}$ systems complex phase transitions were observed. More resistant to the conditions of thermal fatigue are coatings containing aluminum titanate Al$\text{}_{2}$TiO$\text{}_{5}$ and mullite 3 Al$\text{}_{2}$O$\text{}_{3}$-2 SiO$\text{}_{2}$.
Źródło:
Acta Physica Polonica A; 1999, 96, 2; 275-281
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Fluid-Like and Critical Behavior of the Isotropic-Nematic Transition Appearing in Linear and Non-linear Dielectric Studies
Autorzy:
Drozd-Rzoska, A.
Rzoska, S. J.
Zioło, J.
Powiązania:
https://bibliotekanauki.pl/articles/2014495.pdf
Data publikacji:
2000-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Md
64.30.+t
77.22.Ch
Opis:
A short review of literature and the authors' experimental results for the pretransitional behavior in the isotropic phase of nematogens is given. The paper also presents new results of non-linear dielectric effect and dielectric permittivity measurements in the broad temperature range. Results obtained show significant advantages of non-linear dielectric effect and dielectric permittivity for studying pretransitional properties in liquid crystalline materials. The paper contains a comprehensive comparison of the experiment with predictions of the mean-field model and the fluid-like description. The presented analysis strongly supports the image of the isotropic phase as a complex liquid resulting from vicinity of the fluid-like, "nematic-isotropic", critical point.
Źródło:
Acta Physica Polonica A; 2000, 98, 5; 637-643
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Infrared Synchrotron Radiation: from Condensed Matter to Biology Researches
Autorzy:
Marcelli, A.
Iliescu, C.
Powiązania:
https://bibliotekanauki.pl/articles/2028923.pdf
Data publikacji:
2001-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.-j
87.64.-t
87.57.-s
41.60.Ap
87.14.Ee
Opis:
Infrared spectroscopy is probably the oldest spectroscopic method applied to investigate materials and chemico-physical phenomena. Nowadays, infrared spectroscopy represents the characterization technique most applied in the industry and in many technological processes. In the last decades a significant progress has been achieved in the use of the intense and brilliant infrared emission from electron storage rings previously used only as VUV and X-ray sources. In the infrared range the low energy of the electron beam does not affect the synchrotron radiation spectral distribution, while high current will make storage rings the most brilliant infrared sources to be used for infrared spectroscopy and micro-spectroscopy. Infrared micro-spectroscopy is a unique technique that combines microscopy and spectroscopy for purposes of micro-analysis. Spatial resolution, within a microscopic field of view, is the goal of the modern infrared micro-spectroscopy applied to condensed matter physics, materials science, biophysics, and now to medicine. Although limited in spatial resolution, infrared is able to resolve chemistry using the contrast of the absorption lines. Fourier transform-infrared micro-spectroscopy using synchrotron radiation is now able to collect data with 2-4 cm^{-1} resolution on the scale of 10-100 seconds up to an area of a few microns opening a new scenario: infrared spectroscopy of entire cells and tissue. Moreover, distributions of functional groups such as proteins, lipids, and nucleic acids can be achieved inside a single living cell with a spatial resolution of a few microns.
Źródło:
Acta Physica Polonica A; 2001, 100, 5; 647-658
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nanocrystalline and Polycrystalline Phases Present in the Protective Metalloceramic Coatings
Autorzy:
Górski, L.
Pawłowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/2035503.pdf
Data publikacji:
2002-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.50.Ks
81.30.-t
Opis:
New data about the structure of high-temperature resistant metalloceramic plasma sprayed coatings in micro and nano areas are presented. Application of the new instrumental methods: transmission electron microscopy combined with selected area electron diffraction made it possible to obtain these data. The first layer in Ni based metallic bondcoat shows nanocrystalline structure. External ceramic layer based on stabilised ZrO$\text{}_{2}$ is polycrystalline and contains both cubic and tetragonal crystalline phases. Local inhomogeneities in coatings phase composition are determined.
Źródło:
Acta Physica Polonica A; 2002, 102, 2; 295-299
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Applications of the Transport Integrals in Solid-State Physics and in Electron Spin Relaxation
Autorzy:
Radczyk, T.
Hoffmann, S. K.
Goslar, J.
Powiązania:
https://bibliotekanauki.pl/articles/2036991.pdf
Data publikacji:
2003-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.90.+t
76.30.-v
Opis:
Transport integrals I$\text{}_{n}$(Θ$\text{}_{D}$/T) are reviewed with their applications in solid-state physics, molecular dynamics, and electron spin-lattice relaxation. Analytical approximations of I$\text{}_{n}$ for n=2-8 are proposed as applicable for computer fitting procedures in the range of the variable x=Θ$\text{}_{D}$/T from 0.1 to 40. The results are applied for description of the spin-lattice relaxation data collected for Cu$\text{}^{2+}$ ions in triglycine sulphate and are compared with relaxation data for Cu$\text{}^{2+}$ and Mn$\text{}^{2+}$ in (NH$\text{}_{4}$)$\text{}_{2}$Mg(SO$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$O.
Źródło:
Acta Physica Polonica A; 2003, 104, 5; 469-477
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Spin Relaxation of Cu(II) Ions in ZnGeF$\text{}_{6}$·6H$\text{}_{2}$O Crystal with Strong Jahn-Teller Effect
Autorzy:
Idziak, S.
Hoffmann, S. K.
Goslar, J.
Powiązania:
https://bibliotekanauki.pl/articles/2043479.pdf
Data publikacji:
2005-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.90.+t
76.30.-v
Opis:
Cu$\text{}^{2+}$ ions doped to ZnGeF$\text{}_{6}$·6H$\text{}_{2}$O substitute the host Zn$\text{}^{2+}$ ions and undergo a strong Jahn-Teller effect producing nearly axial elongation of the Cu(H$\text{}_{2}$O)$\text{}_{6}$ octahedra with equal population of the three possible deformations at low temperatures as shown by the EPR spectra. Reorientations between these distorted configurations are observed as a continuous shift of EPR lines leading to averaging of the g- and A-tensors. The full averaging is observed at the phase transition temperature 200 K. Electron spin relaxation was measured up to 45 K only, where the electron spin echo signal was detectable. Electron spin-lattice relaxation is governed by the Raman two-phonon process allowing to determine the Debye temperature asΘ$\text{}_{D}$=99 K. There is no contribution of the Jahn-Teller dynamics to the spin-lattice relaxation rate. Electron spin echo decay is strongly modulated by dipolar coupling to the $\text{}^{1}$H and $\text{}^{19}$F nuclei. The phase memory time is governed by instantaneous diffusion at helium temperatures and then by spin-lattice relaxation processes and excitation to the first vibronic level of energyΔ=151 cm$\text{}^{-1}$.
Źródło:
Acta Physica Polonica A; 2005, 108, 1; 177-185
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Vibronic Dynamics of Cu(H$\text{}_{2}$O)$\text{}_{6}$ Complexes and Electron Spin Relaxation in Temperature Dependence of EPR Linewidth in Diamagnetic Tutton Salt Single Crystals
Autorzy:
Hoffmann, S. K.
Goslar, J.
Powiązania:
https://bibliotekanauki.pl/articles/2047171.pdf
Data publikacji:
2006-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.90.+t
76.30.-v
Opis:
EPR linewidth of Cu$\text{}^{2+}$ in the Tutton salt crystals weakly depends on temperature at low temperatures and then it rapidly grows above 60 K. We present detailed results of measurements and analysis for $\text{}^{63}$Cu$\text{}^{2+}$ in K$\text{}_{2}$Zn(SO$\text{}_{4}$)$\text{}_{2}$·6 H$\text{}_{2}$O, K$\text{}_{2}$ Zn(SO$\text{}_{4}$)$\text{}_{2}$·6D$\text{}_{2}$O, (NH$\text{}_{4}$)$\text{}_{2}$Mg(SO$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$O and Cs$\text{}_{2}$Zn (SO$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$O in a temperature range of 4.2-300 K and compare them with already published electron spin-lattice relaxation data. The relaxation contributes weakly to the linewidth which is dominated by molecular dynamics and grows exponentially with temperature. To describe this we are discussing the influence of jumps between two sites of Cu$\text{}^{2+}$ complexes in a slow motion region where the sites are differently thermally populated. This case has not been considered so far. We have derived appropriate expressions describing the contribution of jumps to the linewidth which allows the determination of the jump rate and energy difference δ$\text{}_{A,B}$ between the two sites being two Jahn-Teller distorted configurations of the vibronic Cu(H$\text{}_{2}$O)$\text{}_{6}$ complexes. The jump rate 1/τ strongly depends on temperature and reaches 10$\text{}^{9}$ s$\text{}^{-1}$ at room temperature, whereas theδ$\text{}_{A,B}$ varies from 117 cm$\text{}^{-1}$ for K$\text{}_{2}$Zn(SO$\text{}_{4}$)$\text{}_{2}$·6D$\text{}_{2}$O to 422 cm$\text{}^{-1}$ for Cs$\text{}_{2}$Zn(SO$\text{}_{4}$)$\text{}_{2}$·6 H$\text{}_{2}$O. The comparison with vibronic level splitting, which varies in the range of 67-102 cm$\text{}^{-1}$, indicates that the reorientation mechanism involves phonon induced tunnelling via excited vibronic levels. These reorientations do not contribute, however, to the spin-lattice relaxation which is governed by ordinary two-phonon relaxation processes in the whole temperature range. Thus, the reorientations and spin relaxation are two independent phenomena contributing to the total linewidth.
Źródło:
Acta Physica Polonica A; 2006, 110, 6; 807-816
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical Calculations of Cohesive and Electronic Properties of Quaternary AlGaInN Alloys
Autorzy:
Łopuszyński, M.
Bartoszek, J.
Majewski, J. A.
Powiązania:
https://bibliotekanauki.pl/articles/2047722.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.66.Dk
61.66.-f
62.20.Dc
64.30.+t
Opis:
We present theoretical studies of the AlGaInN nitride quaternary alloys. The studies are based on ab initio calculations performed within the density functional theory and virtual crystal approximation. The equilibrium lattice constants, bulk moduli, and elastic constants were calculated for the whole possible range of concentrations of the alloy constituents. The theoretical values were then fitted with second- and third-order polynomials. For all properties studied, the considerable bowing was observed.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 449-454
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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