Electron spin‐lattice relaxation of Cu²⁺ ions in planar coordination geometries: Calculation and experimental data of T₁ for Cu²⁺ in Ni(II) bis(diethyl‐dithiocarbamate) crystals

Abstract

A general formula is derived for the direct spin-lattice relaxation process of paramagnetic ions with 8 = +for arbitrary orientations of an external magnetic field relative to the crystal axes. Using the formula obtained, Tl of Cuzt ions in square planar coordination geometries is calculated in the point charge approximation. The temperature, concentration, and angular dependence of TI of Cu2+ ions in Ni(II)bis(diethyl-dithiocarbamate) single crystals are reported. Including some features of covalency a reasonable agreement between the theoretical and experimental values of T, is reached. Es wird von detaillierten Untersuchungen zur Temperatur-, Konzentrations-und Winkelabhingigkeit der Spin-Gitter-Relaxationszeit TI von Cutt -1onen in Ni(II)bis(diLthyldithiocarbamat)-Einkristallen berichtet. Fur den direkten RelaxationsprozeB von paramagnetischen Ionen mit S = -:wird eine allgemeine Beziehung abgeleitet, die die Berechnung von T, fur beliebige Magnetfeldorientierungen gestattet. Ausgehend von dieser Beziehung wird die Berechnung von T, fiir Cii2+-Ionen in quadratisch planaren Koordinationsgeometrien im Rahmen der Kristallfeldtheorie beschrieben. Die teilweise Berucksichtigung der Kovalenz fuhrt zu einer verniinftigen tfbereinstimmung mit den experimentellen Daten.

Vibronic Behavior and Electron Spin Relaxation of Jahn−Teller Complex Cu(H2O)62+ in (NH4)2Mg(SO4)2·6H2O Single Crystal

“…29 The Orbach-type exp(-E/kT) relaxation was observed for Cu 2+ in Zn(BrO 3 ) 2 ‚6H 2 O, 36 although the T 1 -1 ∝ T 3 dependence was reported for this crystal also. 37 In the all of the above crystals and for Cu 2+ in (NH 4 ) 2 Mg(SO 4 ) 2 ‚6H 2 O the T 1 values in the temperature range 4.2-10 K are of the order of T 1 ) 10 -4 s. This is shorter but not significantly than T 1 for Cu 2+ in crystals without Jahn-Teller effect, e.g., T 1 ) 3 × 10 -4 s for Cu 2+ in triglycine selenate at 10 K, 41 T 1 ) 1 × 10 -2 s for Cu 2+ in Ni bis(diethyldithiocarbamate) at 10 K, 42 and T 1 ) 5 × 10 -2 s for Cu 2+ in LiNbO 3 at 10 K. 43 To have a direct proof that Jahn-Teller dynamics governs the spin relaxation in our crystal, we have measured T 1 for Mn 2+ ions in (NH 4 ) 2 Mg(SO 4 ) 2 ‚6H 2 O along the z-axis direction of the Cu 2+ complex, and we found that at 10 K the T 1 (Mn 2+ ) ) 1 × 10 -2 s. 44 The Mn 2+ is not a Jahn-Teller ion, and its relaxation in the same host lattice is of about 2 orders of magnitude slower than Cu 2+ , indicating a dominat role of the Jahn-Teller dynamics in electron spin relaxation.…”

Electron spin relaxation of copper(II) ions in diamagnetic crystals

“…[12], Ni(diethyldithiocarbamate) 2 (Op = 80 K) [13], LiNbO 3 (Op = 250 K) [7], and triglycine selenate (TGSe) (OD = 168 K) [6]. The Debye temperatures were determined from the relaxation data with the best fit presented by solid lines.…”

Electron spin resonance

“…The structure and single crystal ESR spectra of Cu(imidazole)4(N03)2 have been described (179). Spin-lattice relaxation for Cu(II) in nickel®) diethyldithiocarbamate has been treated theoretically and experimentally with reasonable agreement between the two (180). Single crystal ESR studies of six-coordinate bis(o)-nitrophenonato)bis(4-methylpyridine)copper(II) in the corresponding zinc(II) chelate have been reported (181).…”