The yttrium‐stabilised electron‐hole centres in anhydrite

Abstract

EPR has beenused to study yttrium-stabilised electron-hole centres of natural anhydrites. Geometrical models have been constructed by measuring the main directions of the tensors of the spectroscopic constants accurately and by correlating them with the crystal structure. Hyperfine splitting constant and thermal stability of the centres have been shown to vary as the localization of the unpaired electron density at the yttrium ions which replace calcium of the initial lattice.Mittels EPR wurden Yttrium-stabilisierte Elektron-Loch-Zentren in natiirlichem Anhydrit untersucht. Geometrische Modelle werden durch genaue Messung der Hauptwerte der Tensoren der spektroskopischen Konstanten und durch Korrelation mit der Kristallstruktur konstruiert. Es wird gezeigt, daB die Hyperfeinaufspaltungskonshnte und die thermische Stabilitiit der Zentren wie die Lokalisierung des ungepaarten Elektrons am Yttriumatom variiert, das das Kalziumatom des urspriinglichen Gitters ersetzt.

ESR investigation of gamma irradiated sulbactam sodium

“…4, respectively. Calculated rhombic g values correlate well with both experimental g values determined in the present work for strong resonance peaks: 8 (g 8 = 2.0082); 9 (g 9 = 2.0057); 10 (g 10 = 2.0022) and with those reported in the literature for SO 2 − ionic radical induced in sulphur containing compounds irradiated by gamma radiation [7][8][9][10][11][12][13][14]. In fact, SO 2 is the most sensitive sub group to radiation in SS molecule due to its high electrophilic feature, and is expected to be at the origin of the observed three strong resonance lines dominating ESR spectra through the formation of SO 2 − ionic radical species that is called radical B in the present work.…”

“…Spectroscopic parameters determined from spectrum simulation calculations for proposed tentative radical species were found to correlate well with those reported in the literature for similar radicals [8][9][10][11][12][13][14][19][20][21]. Radical species A and B are relatively stable at room temperature, however, species B has a higher activation energy (E B = 82(±3) kJ/mol) than the species A (E A = 46(±4) kJ/mol).…”

“…The results of the microwave saturation studies indicate that, although, peaks 7 and 11 belong to weak peaks, their intensities increase much faster than the other weak peaks but much slower than the intensities of strong peaks. This shows that weak peaks appearing just at the left and right sides of the strong central peaks (8)(9)(10) are affected heavily from the presence of the strong peaks. …”

“…However, critical point in this respect is the choice of mathematical function(s) used to describe the dose-response curve, that is, signal intensity calculated by double integration technique versus applied dose curves. Strong peaks (8)(9)(10) only, arising from species B, were considered in the evaluation of dosimetric feature of gamma irradiated SS due to its high radiation yield toward species B in the dose range of (0-10 kGy) more suitable for radiation dose measurements. The results obtained concerning the variation of signal intensity with applied dose are given in Fig.…”

ESR Dating of Marine Barite in Chimneys Deposited from Hydrothermal Vents

“…The observed signal is attributed to the electronic SO 3 -centre (Ryabov et al, 1983;Kasuya et al, 1991) with a structure similar to the E' centre in SiO 2 and CO 2 -centre in CaCO 3 (Kasuya et al, 1991). The g factors are 2.0034, 2.0022, and 1.9995, and are consistent with those reported by Ryabov et al (1983) (Bershov et al, 1971). Therefore, the contents of a M 3+ ion in marine barite may be different from that in natural barite on land.…”