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Wyszukujesz frazę "Goslar, T." wg kryterium: Wszystkie pola


Wyświetlanie 1-3 z 3
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
    Wyświetlanie 1-3 z 3

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