Paramagnetic resonance of metal ions and defect centers in topaz

Abstract

231should exhibit a linear relationship between two variables with different slopes but possibly with very nearly the same intercept. In order to improve on the precision of the slopes, a common intercept was assumed in the general least-squares adjustment using data for all compounds. Using the technique developed in this paper, the n + 1 square matrix (n = number of compounds) which would ensue from the general solution was reduced to the solution of 2n 2 X 2 matrices.Aclcnowledgments. The authors express their appreciation to the Robert A. Welch Foundation for the financial support of this work. Also, one of the authors (E. C.) is the recipient of a NASA Traineeship for predoctoral work in chemistry and is grateful for this assistance. Finally, we wish to express our appreciation to Miss Marie Cobb for hand calculations and assistance in preparing the programs and to Miss Elsie Bryan for assistance in preparing the manuscript.Electron paramagnetic resonance (epr) of Fea+ impurities in colorless topaz was measured at 77 and 300°K with X-band frequencies. The most intense peaks occurred at ~~~ (1) This work was supported by the U. 8. Atomic Energy Commission.

Correlations of Electron Spin Resonance Parameters with Fe3+ Sites in Topaz

“…Lacking a knowledge of the eigenvalues of the field gradient tensors for Fe3+ sites we cannot offer a preference for solution I over solution 11. It will be noted that our solution I assignment corresponds to that advanced by Dickenson and Moore [7], the labelling of the x-, y-, and z-axes in their result being in agreement with that of Thyer, Quick, and Holuj [6].…”

“…Results were interpreted in terms of FeS+ and one spin-Hamiltonian, but no discussion of axes was given and no direction cosines were reported. Dickenson and Moore [7] discuss eight non-equivalent sites for AP+ and a center of inversion which reduces the number of types of inequivalent sites to four. Results were given for one spinHamiltonian for Fe3+ and again no direction cosines were reported.…”

ESR spectrum of Fe+3 in topaz. II. Superhyperfine structure

“…Several recent papers discussed the fine structure (fs) of the electron paramagnetic resonance (EPR) spectrum of Fe+3 in topaz, A1204(OH, F), (Denison, Ensign, and Sims 1967;Dickinson and Moore 1967;and Thyer, Quick, and Holuj 1967). The last reference, designated henceforth as I for brevity, originated from this laboratory.…”

The topaz-bearing rhyolites from the San Luis Potosi area (Mexico): characteristics of the lava and growth conditions of topaz

“…9). The EPR-spectrum of amber-colored topaz exhibits several lines that are related to X (hole-center e + ) and A and B (electron centers e -) color-centers [nomenclature according to Dickinson and Moore, 1967]. In contrast to that of the amber-colored topaz, the EPR-spectrum of the colorless crystals does not show additional lines that can be assigned to color centers.…”

“…but to the presence of the color-centers X, A and B. According to Dickinson and Moore [1967], these color centers are only stable below 500 o C. The colorless gemstones thus crystallized first at a temperature above 500 o C, whereas the amber-colored topaz crystallized later, in the axis of the system and at a lower temperature, below 500 o C. The presence of only one color center (X) in the Cerro El Lobo topazes could indicate a temperature around 500 o C. The disappearance of a color center after the crystallization of an amber-colored topaz can occur by heating above 500 o C, and its appearance in a colorless crystal can be the result of gamma irradiation [Nassau and Prescott, 1975]. Such possibilities are here excluded because both amber-colored and colorless crystals are hosted in the same rhyolite and are located in the same part of the dome, at only some meters from each other.…”