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Tytuł:
Phonon Drag and Carrier Diffusion Contributions in Thermoelectric Power of $M_3C_{60}$ (M = K, Rb) Fullerides
Autorzy:
Varshney, D.
Singh, N.
Powiązania:
https://bibliotekanauki.pl/articles/1400154.pdf
Data publikacji:
2013-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.Wz
74.25.fg
74.25.Kc
Opis:
The thermoelectric power (S) of $M_3C_{60}$ (M = K, Rb) alkali intercalated fullerides is theoretically investigated by considering the Mott expression within parabolic band approximation to reveal the electron diffusive thermoelectric power $(S_{c}^{diff})$. We follow the Fermi energy as electron parameter and $S_{c}^{diff}$ discerned linear temperature dependence. S infers a change in slope above transition temperature and becomes almost linear above 70 K for $M_3C_{60}$ alkali intercalated fullerides. As a next step, the phonon drag thermoelectric power $(S_{ph}^\text{drag})$ is computed within relaxation time approximation when thermoelectric power is limited by scattering of phonons from defects, grain boundaries, phonons and electrons as carriers. It is noticed that the $S_{ph}^\text{drag}$ of $K_3C_{60}$ is anomalous and it is an artifact of strong phonon-electron and -phonon scattering mechanism. The thermoelectric power within relaxation time approximation has been taken into account ignoring a possible energy dependence of the scattering rates. Behaviour of S(T) is determined by competition among the several operating scattering mechanisms for the heat carriers and a balance between carrier diffusion and phonon drag contributions in $M_3C_{60}$ (M = K, Rb) alkali intercalated fullerides.
Źródło:
Acta Physica Polonica A; 2013, 123, 4; 752-760
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vibration and Luminescence Spectroscopic Investigations of the Alkali Rare Earth Double Phosphates M$\text{}_{3}$(RE,Eu)(PO$\text{}_{4}$)$\text{}_{2}$ (M=K, Rb; RE=La, Gd)
Autorzy:
Kloss, M.
Schwarz, L.
Hölsä, J. P. K.
Powiązania:
https://bibliotekanauki.pl/articles/1995573.pdf
Data publikacji:
1999-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.50.-f
61.66.Fn
63.20.-e
71.20.Dg
71.20.Eh
71.70.-d
78.30.-j
78.55.-m
Opis:
The room temperature IR- and Raman spectra of the different M$\text{}_{3}$RE(PO$\text{}_{4}$)$\text{}_{2}$ (M = K, Rb; RE = La, Eu, Gd) double phosphates were analysed and used to interpret the vibronic side band structure in the photoluminescence spectra. The intraconfigurational 4f-4f electronic transitions in the photoluminescence spectra of the Eu$\text{}^{3+}$ doped M$\text{}_{3}$RE(PO$\text{}_{4}$)$\text{}_{2}$ were analysed in detail. The crystal field fine structure of the $\text{}^{5}$D$\text{}_{0}$ → $\text{}^{7}$F$\text{}_{J}$ (J=0-4) transitions was analysed accounting for the information on the crystal structure. The effect of the temperature as well as the alkali host cation was evaluated. Finally, a preliminary crystal field energy level scheme for the $\text{}^{7}$F$\text{}_{J}$ (J=0-4) ground term was deduced from the analysis of the photo-luminescence as well as IR- and Raman spectra.
Źródło:
Acta Physica Polonica A; 1999, 95, 3; 343-349
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Physical Characterization of $Sb_2O_3-M_2O-MoO_3$ (M~= Li,~K) New Glasses
Autorzy:
Soltani, M.
Hamzaoui, M.
Houhou, S.
Touiri, H.
Bediar, L.
Ghemri, A.
Petkova, P.
Powiązania:
https://bibliotekanauki.pl/articles/1399699.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.70.Ce
78.20.Ci
78.30.-j
Opis:
New heavy metal oxide glasses involving $Sb_2O_3$ have been investigated. By using classical routes (melting-casting), glasses synthesized in silica crucibles were obtained in the combination of ternary systems $Sb_2O_3-M_2CO_3-MoO_3$ (M = Li and K). Characteristic temperatures such as glass transition $T_{g}$, and onset of the crystallization $T_{x}$, have been measured using differential scanning calorimeter. Ultrasonic velocities were measured by using pulse echo method to determine the elastics parameters, such as elastic modules (E, G, K, L). Other physical properties were measured, such as density and optical transmission window in far infrared spectra using KBr pellets. Influence of composition on these physico-chemical properties is discussed and correlated to the glass structure.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 227-229
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Third Harmonic Generation Susceptibility of Polyacetylene in Terms of the Chain Temperature
Autorzy:
Sabra, M. K.
Powiązania:
https://bibliotekanauki.pl/articles/2046843.pdf
Data publikacji:
2006-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ph
78.66.Qn
42.65.An
Opis:
The tight binding Hamiltonian of Su, Schrieffer, and Heeger has been used to describe the physical properties of the polyacetylene chain. The chain temperature is calculated from the potential energy which is directly related to the CH group displacement. Two different forms of the displacements have been considered: random and Gaussian. The third harmonic generation susceptibility spectra have been plotted in terms of the temperature using the four-wave mixing formula. The results show that a second peak at the mid gap energy has occurred for room temperature which is in good agreement with the experimental data.
Źródło:
Acta Physica Polonica A; 2006, 109, 6; 761-774
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Long-Range Interactions and the Oscillator Strength for the $\text{}^{1}1_{u}, \text{}^{1}0_{u}^{+}$ ← X $\text{}^{1}0_{g}^{+}$ Transitions in Zn$\text{}_{2}$
Autorzy:
Kubkowska, M. K.
Szczęśniak, T. M.
Grycuk, T.
Powiązania:
https://bibliotekanauki.pl/articles/2037211.pdf
Data publikacji:
2004-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
32.70.-n
32.70.Cs
32.70.Jz
33.70.-w
34.20.-b
Opis:
The interaction potentials for Zn$\text{}_{2}$ electronic states $\text{}^{1}1\text{}_{u}$ and $\text{}^{1}0_{u}^{+}$ correlated with (4 $\text{}^{1}P_{1}$+4 $\text{}^{1}S_{0}$) asymptote in the long-range region (10-25) Å and the oscillator strength f for the absorption transition to these states are derived experimentally from a careful analysis of the self-broadened resonance 213.8 nm line of Zn. It is found that although the interatomic interactions at so long distances are dominated by resonance potential of the form C$\text{}_{3}$/R$\text{}^{3}$ resulting in the Lorentzian line shape, the parameter C$\text{}_{3}$ and thus f value significantly decrease with R decreasing. This effect proved to be a linear function of R$\text{}^{-1}$ yielding the oscillator strength for the considered line f$\text{}_{0}$=1.456 $\pm$ 0.010 from $R \rightarrow \infty$ extrapolation. This value seems to be the most accurate experimental result as yet and shows that the best theoretical values for this quantity are overestimated. It is suggested that the long-range behaviour of the potential energy curves observed here for the first time represents the effective potentials including dominating resonance interactions and a possible slight contribution of the dispersion interactions as well as the R-dependent spin-orbit interaction.
Źródło:
Acta Physica Polonica A; 2004, 105, 4; 317-328
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Specific Heat of (NH$\text{}_{2}$(CH$\text{}_{3}$)$\text{}_{2}$)$\text{}_{3}$Bi$\text{}_{2}$I$\text{}_{9}$
Autorzy:
Plackowski, T.
Włosewicz, D.
Tomaszewski, P. E.
Baran, J.
Marchewka, M. K.
Powiązania:
https://bibliotekanauki.pl/articles/1932127.pdf
Data publikacji:
1995-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Kb
65.40.-f
Opis:
The specific heat of title compound was measured by adiabatic calorimeter in the temperature range 80-315 K. The phase transitions at about 304, 285 and 235 K were confirmed. A new structural phase transition at about 125 K was observed as well as new anomaly on differential scanning calorimetry (DSC) curve at about 318 K. The peculiar multiple character of C, anomalies may be explained in terms of phase transitions or intermediate phases induced by impurities. The specific heat data are in agreement with the independent DSC measurements and with preliminary X-ray studies.
Źródło:
Acta Physica Polonica A; 1995, 87, 3; 635-641
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigating Mechanisms of Radiation-Induced DNA Damage Using Low-Energy Photons
Autorzy:
Folkard, M.
Prise, K. M.
Powiązania:
https://bibliotekanauki.pl/articles/2044651.pdf
Data publikacji:
2006-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
87.50.-a
Opis:
Central to any mechanistic biophysical model of radiation damage to DNA is the relationship between the amount and distribution of energy deposited in the DNA helix and the subsequent production of DNA damage. It is now clear from a number of studies that the minimum energy required to produce bond breaks in DNA is significantly lower than might be expected. For example, some biophysical models have assumed that it takes several 10s of eV to produce a double-strand break in DNA. However, using low-energy photons, we have shown that energy depositions as low as 7 eV can induce double-strand break and that this is enhanced when the DNA is hydrated, showing that free radical damage is also important.
Źródło:
Acta Physica Polonica A; 2006, 109, 3; 265-271
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Role of Ionic Processes in Degradation of Wide-Gap II-VI Semiconductor Materials
Autorzy:
Borkovskaya, L.V.
Dzhymaev, B.R.
Korsunskaya, N.E.
Markevich, I.V.
Singaevsky, A.F.
Sheinkman, M.K.
Powiązania:
https://bibliotekanauki.pl/articles/1858211.pdf
Data publikacji:
1998-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Jv
78.55.Et
Opis:
A role of mobile defects in processes responsible for II-VI compound semiconductor characteristic instability is under consideration. These defects have been shown to be responsible for electron-enhanced reactions in these materials, in particular, shallow donor creation in CdS crystals. Accumulation of mobile defects near dislocations results in some specific effects: anisotropy of conductivity induced by electric field and distortion of edge emission spectrum shape. These effects side by side with electron-enhanced defect reactions have been found to influence considerably semiconductor device characteristics.
Źródło:
Acta Physica Polonica A; 1998, 94, 2; 255-259
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nano-Optics on Individual Quantum Objects - From Single to Coupled Semiconductor Quantum Dots
Autorzy:
Bacher, G.
Schömig, H.
Welsch, M. K.
Scheibner, M.
Seufert, J.
Obert, M.
Forchel, A.
Maksimov, A. A.
Zaitsev, S.
Kulakovskii, V. D.
Powiązania:
https://bibliotekanauki.pl/articles/2035563.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.Hc
75.50.Pp
73.21.La
Opis:
Some recent highlights of our optical studies on single and coupled semiconductor quantum dots are reviewed. In the first part, we concentrate on the role of spins and spin-spin interaction in nonmagnetic and magnetic single quantum dots. In the case of strictly resonant excitation of the ground state in self-assembled CdSe/ZnSe quantum dots, we find an exciton spin relaxation time, which exceeds the recombination lifetime significantly. Linear polarization has to be used for these experiments, as the electron-hole exchange interaction lifts the spin degeneracy and the eigenstates are linear combinations of spin-up and spin-down excitons. In a magnetic quantum dot, the exchange interaction between carrier spins and the spins of magnetic ions is shown to be responsible for giant magneto-optical effects. We demonstrate the formation of zero-dimensional magnetic polarons and we succeeded in measuring the magnetization on a scale of a few nanometers using the characteristic photoluminescence signal of individual quantum dots as experimental monitor. The second part is devoted to pairs of single quantum dots. On one hand, single exciton tunneling within an individual quantum dot pair is demonstrated studying single pairs of vertically correlated strain-induced and self-organized quantum dots. On the other hand, we show that in a pair of lithographically defined single dots with strongly different g-factors the energy spacing between the dot ground states can be tuned in an external magnetic field by about 10 meV, giving access to a controlled coupling between two individual quantum dots.
Źródło:
Acta Physica Polonica A; 2002, 102, 4-5; 475-494
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Properties of a Semimagnetic Quantum Well in a Proximity of a Superconducting Film
Autorzy:
Lebecki, K. M.
Kłopotowski, Ł.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/2044492.pdf
Data publikacji:
2005-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.De
74.25.Qt
Opis:
We consider, via numerical calculations, a hybrid structure made of a semimagnetic Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te quantum well deposited in a close proximity to superconducting niobium film. We simulate photoluminescence and the Faraday rotation spectra, modified by the presence of vortices in this type II superconductor. The magnitude of the evaluated effects is small - the vortex induced spectral line shape variation is of the order of 1% at 1 K and 0.1% at 3 K and is expected to occur mainly in the field range between 0.03 T and 0.05 T.
Źródło:
Acta Physica Polonica A; 2005, 108, 5; 741-748
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anomalous Transport Properties of Carbon-Doped $EuB_6$
Autorzy:
Batkova, M.
Batko, I.
Filipov, V.
Flachbart, K.
Sechovský, V.
Shitsevalova, N.
Šantavá, E.
Šebek, J.
Powiązania:
https://bibliotekanauki.pl/articles/1534309.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
72.15.Gd
75.47.Gk
Opis:
In the presented work we report electrical, magnetic and thermal properties of $EuB_{6-x}C_{x}$ single crystals with an estimated value of x ≈ 0.07. Our studies reveal an antiferromagnetic phase transition at $T_{N}$ ≈ 6.7 K. Electrical resistivity at zero magnetic field shows a pronounced resistivity maximum at $T_{M}$ ≈ 7 K, just above the antiferromagnetic phase transition temperature. With increasing applied magnetic field the maximum moves to lower temperature and becomes totally suppressed at the field of 9 T. Observed magnetoresistance is negative in the whole studied temperature range 2-20 K, yielding a ratio of ρ(0 T, 7 K)/ρ(9 T, 7 K) ≈ 2.5. The origin of such magnetoresistance is associated with formation of mixed magnetic structure in the system due to fluctuation of carbon concentration.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 893-894
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Understanding Radiation Damage to Cells Using Microbeams
Autorzy:
Folkard, M.
Prise, K. M.
Shao, C.
Gilchrist, S.
Schettino, G.
Michette, A. G.
Vojnovic, B.
Powiązania:
https://bibliotekanauki.pl/articles/2044649.pdf
Data publikacji:
2006-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
41.75.Ak
87.50.-a
Opis:
Cellular micro-irradiation techniques provide unique experimental opportunities for understanding how ionizing radiation interacts with living cells and tissues. Using microbeams, it is possible to deliver precise doses of radiation to selected individual cells, or sub-cellular targets in vitro. This technique continues to be applied to the investigation of a number of phenomena currently of great interest to the radiobiological community. In particular, it is the study of so-called "non-targeted" effects (where cells are seen to respond indirectly to ionizing radiation) that are benefiting most from the use of microbeam approaches.
Źródło:
Acta Physica Polonica A; 2006, 109, 3; 257-264
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The magnetocaloric effect in {[Cu(bapa)]₃[Cr(CN)₆]₂}ₙ · 6n H₂O at low temperatures
Autorzy:
Ráczová, K.
Vavra, M.
Hegedüs, M.
Čižmár, E.
Powiązania:
https://bibliotekanauki.pl/articles/1048121.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.30.Gw
75.10.Pq
Opis:
The crystals of {[Cu(bapa)]₃[Cr(CN)₆]₂}ₙ·6nH₂O (bapa = bis(3-aminopropyl)amine) are formed by infinite Cu(II)-Cr(III) antiparallel chains, which are connected into the third direction by additive [Cu(bapa)] moieties. The onset of long-range magnetic order at 3.2 K was observed by AC susceptibility. The study of the magnetocaloric effect from magnetization measurements yields a large entropy change -ΔS_{M} = 13.65 J K¯¹mol¯¹ (-ΔS_{M} = 12.25 J kg¯¹K¯¹) at the field change from 0 T to 3 T at temperature 4 K. The analysis of the critical behavior of -ΔS_{M} suggests the value of critical exponent n = 0.577 at the ordering temperature characteristic for three-dimensional magnets with Ising anisotropy.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 429-431
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Transport and Point Contact Spectroscopy of Cubic DyCu$\text{}_{5}$
Autorzy:
Nenkov, K.
Idzikowski, B.
Ilkovic, S.
Kačmarčiková, E.
Reiffers, M.
Müller, K.
Powiązania:
https://bibliotekanauki.pl/articles/2013688.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Eh
72.15.Eb
73.23.Ad
73.40.Jn
Opis:
The electron transport properties and point contact spectra of melt-spun DyCu$\text{}_{5}$ with the cubic phase (structure type AuBe$\text{}_{5}$, space group $F\overline{4}3m$) were investigated. It was found by ac-susceptibility measurements that below a transition temperature T$\text{}_{m}$=6.5 K this phase shows metamagnetism. Between T$\text{}_{m}$ and T$\text{}_{C}$=14.5 K a spontaneous magnetization is found. Our measurements of electrical resistivity confirm the existence of two magnetic phase transitions in the compound. Furthermore, we present point contact spectra of DyCu$\text{}_{5}$-Cu heterocontacts which are directly proportional to the electron-quasiparticle interaction function. Apart from a peak at about 18 meV, which is characteristic of electron-phonon interaction in pure Cu, we observed a series of additional maxima at lower energy, which are connected with the allowed 4f-transitions from the ground state to excited crystalline electric field levels.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 843-846
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optically Active Si:Er Layers Grown by the Sublimation MBE Method
Autorzy:
Stepikhova, M.
Andreev, A.
Andreev, B.
Krasil'nik, Z.
Shmagin, V.
Kuznetsov, V.
Rubtsova, R.
Jantsch, W.
Ellmer, H.
Palmetshofer, L.
Preier, H.
Karpov, Yu.
Piplits, K.
Hutter, H.
Powiązania:
https://bibliotekanauki.pl/articles/1992203.pdf
Data publikacji:
1998-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.15.Hi
Opis:
We report the first application of sublimation molecular beam epitaxy to grow uniformly and selectively doped Si:Er layers with Er concentration up to 5×10$\text{}^{18}$ cm$\text{}^{-3}$. The Hall concentration of electrons is about 10% of total Er contents. The mobility is 300-400 cm$\text{}^{2}$ V$\text{}^{-1}$ s$\text{}^{-1}$ at 300 K. All samples exhibit photoluminescence at 1.537 μm up to 100-140 K.
Źródło:
Acta Physica Polonica A; 1998, 94, 3; 549-554
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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