EPR and Optical Absorption Studies of VO2+ Doped Trisodium Citrate Dihydrate Single Crystals
The electron paramagnetic resonance of VO2+ doped trisodium citrate dihydrate (Na3C6H5O7·2H2O) single crystals and powder has been examined at room temperature. The angular variation of the EPR spectra has shown that two different VO2+ complexes are located in different chemical environments, each environment containing two magnetically inequivalent VO2+ sites in distinct orientations occupying substitutional positions in the lattice and showing a very large angular dependence. The crystalline field around the VO2+ ion is nearly axial. The optical absorption spectrum shows three bands, centered at 24631, 16892, and 12195 cm−1. The spin Hamiltonian parameters and the molecular orbital coefficients are calculated from the EPR and optical data, and result are discussed. Keywords EPR; Trisodium Citrate; Absorption the Spectrum; Vanadyl Ion
Evaluation of EPR parameters for compressed and elongated local structures of VO2+ and Cu2+ spin probes in BaO-TeO2-B2O3 glasses
Abstract EPR parameters and the local configurations of the transition metal (TM) ions VO2+ and Cu2+ in BaO-TeO2-B2O3 glasses were experimentally evaluated and also theoretically verified. From the recorded X-band EPR spectra the spin-Hamiltonian parameters (SHP) were determined. The optical spectra of vanadium doped glass samples revealed a single absorption band at 596 nm which was assigned to 2B2g → 2B1g transition, whereas copper doped glasses revealed two absorption bands around 818 and 602 nm which were assigned to 2B1g → 2B2g and 2B1g → 2E2g transitions respectively. Theoretical studies were accomplished on the EPR and optical factors from perturbation theory. It was observed from both the experimental and theoretical SHP values of vanadium containing glasses that the VO2+ ions are in tetragonally compressed octahedral sites with dxy (2B2g) ground state, while the copper containing glasses found to be in tetragonally elongated octahedral sites with d x 2 − y 2 (2B1g) as the ground state. It is found that the magnitude of the relative tetragonal compression ratio ( φ ) of vanadium ion is less than the relative tetragonal elongation ratio ( τ ) of copper ion. The nature of the bonding between TM ions (i.e. vanadium and copper) and their ligands was assessed. Theoretical and experimental EPR parameters are in great concurrence with each other.
Hutcheson's Moral Sense Theory Reconsidered
There is no more central feature of Francis Hutcheson's moral philosophy than his theory of the moral sense. In the past this sense or faculty was widely understood to be a distinctive and independent sense devoted to the apprehension of moral qualities, but William Frankena has in recent years challenged this traditional view of Hutcheson's theory, and offered in its place an emotivist interpretation. Without question Frankena's study was of the first importance, in that it seems to have overturned the much too simplistic traditional view of the moral sense. Unfortunately, however, Frankena's own interpretation of the moral sense is as inadequate and misleading as the view he overturns, for he concludes that the moral sense is not at all a cognitive faculty, that it does not, that is, apprehend moral qualities, but, rather, is a faculty that enables and motivates us to feel, express, and evoke moral emotions. The moral sense, he argues, is “the source of the feelings involved” in moral approbation or disapprobation, and this approbation is “wholly non-cognitive, very much as it is on Ayer's more recent [emotivist] view … This, I shall show, is much too narrow a view; Hutcheson did not limit the moral sense to a single function, nor did he — lacking as he did twentieth-century perspectives — find it either necessary or desirable to assume that the domains of the cognitive and the emotive (or affective) were mutually exclusive.