EPR, ELECTRON SPIN-LATTICE RELAXATION, AND DEBYE TEMPERATURE OF CU(II)-DOPED TRIGLYCINE SELENATE CRYSTAL

Single-crystal rotational data of CW-EPR and two-pulse field-swept ESE collected at room and low temperatures lead to the spin-Hamiltonian p arameters g(z) = 2.2596, g(y) = 2.0647, g(x) = 2.0529, A(z) = 151.2 x 10(-4) cm(-1), A(y) = 2.5 x 10(-4) cm(-1), and A(x) = 42.2 x 10(-4) cm (-1) which are temperature independent. The parameters and Cu2+ ion si te in the crystal unit cell are very similar to those in the triglycin e sulfate crystal, Electron-spin-echo measurements of the spin-lattice relaxation time T-1 in the temperature range 4.2-90 K gave identical results for inversion- and saturation-recovery methods, indicating a n egligible spectral-diffusion contribution. The T-1 decreases from 275 mu s at 15 K to 1.7 mu s at 83 K and the temperature dependence is gov erned by the direct (one-phonon) process at low temperatures and two-p honon Raman process at higher temperatures. A new analytical form of t he I-8 transport integral of the Raman term is proposed, The best fit to the theoretical expression was found for the Debye temperature Thet a(D) = 168 +/- 3 K which is comparable to Theta(D) = 171 K calculated from the elastic constants of the crystal. (C) 1996 Academic Press, In c.