EPR Spectrum of Fe3plus;in Synthetic Brown Quartz

摘要

A detailed description is given of the EPR spectrum of Fe3plus;in synthetic brown quartz (the sohyphen;calledIcenter, presumed to be interstitial). There are three equally populated sites differing only in the orientation of their principal axes, which coincide with the three twofold axes of quartz. The values of the Hamiltonian parameters that fit the data best are:gthinsp;equals;thinsp;2.0039, C20lpar;equiv;Drpar;thinsp;equals;thinsp;734.3G, C22lsqb;equiv;lpar;61thinsp;sol;thinsp;2thinsp;sol;thinsp;2rpar;verbar;thinsp;Ethinsp;verbar;rsqb;thinsp;equals;thinsp;401.7G, C40thinsp;equals;thinsp;2.52G, C44thinsp;equals;thinsp;1.40G, where theClmare the coefficients of the Racah operators in the Hamiltonian. Lobes of theV22, V42, andV44parts of the crystalhyphen;field potential point 0.7deg;, 29.5deg;, and 26.8deg;, respectively, from the optic axis of quartz. The occurrence of irregular offhyphen;axis extrema of the line positions when the magnetic field is directed in the vicinity of the optic axis precludes the assignment of magnetic axes of the paramagnetic center in the usual way. All features of the spectrum are predicted accurately by computer calculations based on the derived Hamiltonian. Although the data are not conclusive evidence, they are believed to be more consistent with an assignment of theIcenter to a substitutional site.