Isotope effects in the ESR ofMn++in Ca(OH)2

Abstract

Large differences in the values of the spin-H~~i&tonian parameter b, were observed in Ca(OH), and Ca(OD), at low temperatures, but were not detected in the remaining measured parameters. b, were analyzed in terms of lattice vibrations. The significance of the results for the rema'»ng parameters is also discussed.

A multifrequency EPR approach to travertine characterisation

“…In order to obtain consistent and reliable parameter values, the simpler high-frequency spectra were simulated first. The simplest way to explain both the relevant experimental features, i.e., intensity trend and indentation, is the assumption of a small hyperfine anisotropy for Mn(II) in a distorted octahedral coordination [16]. The best-fit simulations resulted in a close reproduction of both the indentation and the intensity trend, but miss the position of the third, fourth, and fifth lines of 0.1 mT.…”

“…Holuj and Kwan [16], in their EPR study of Mn in Ca(OH) 2 crystals, presented two distinct g-tensor components. This was in agreement with the crystal field assumptions, and the difference between the values reported was within the experimental uncertainty.…”

Paramagnetic resonance studies of phase transitions in condensed materials

“…Generally, the experimental analysis has assumed only coupling to one mode, and, in most cases, the nature of the mode coupling to the ion is unknown. In the case of an impurity ion requiring charge compensation, such as the Mn2+ in NaCl, the dominant coupling is likely to be to local mode vibrations of the defect (Pfister et al, 1969;Owens, 1977b contributions from the lattice modes (Holuj and Kwan, 1974). Generally above liquid nitrogen temperatures, the temperature dependence becomes linear because h o i 9 2kT and, then,…”

Investigations on the local structure and spin Hamiltonian parameters for the orthorhombic Cu2+ center in Ca(OD)2

“…For example, the EPR investigations have been carried out for Cu 2+ -doped Ca(OD) 2 , and the spin Hamiltonian parameters (the g factors g i (i = x, y, z) and the hyperfine structure constants A i ) were measured for one orthorhombic Cu 2+ center (spectrum II) [12]. To explain the above EPR results, the simple second order perturbation formulas of the spin Hamiltonian parameters for a 3d 9 ion under elongated octahedra were adopted in the previous work [12]. However, there are some imperfections in their treatments.…”

“…These materials also exhibit unique structural and vibrational [3], high pressure [4,5], and spectral properties [6][7][8]. In particular, local structure studies of these crystals doped with some transition metal ions (e.g., Mn 2+ , Co 2+ ) have extensively been performed by means of the electron paramagnetic resonance (EPR) technique [9][10][11]. Among the transition metal ions, copper (Cu 2+ ) is a model system with a single 3d hole, corresponding to only one ground state and one excited state under ideal octahedral crystal fields.…”