W. Kaminsky, P.A. Thomas, A.M. Glazer: Optical rotation in Rb TiOAsO4 (PG mm2). Z. Kristallogr. 217 (2002) 1-7.

Measurement of optical rotation in RbTiOAsO4 with the tilter method resulted in a rotatory power of d12= +17(3)o/mm at a wavelength of 670nm, when a (100) sample was tilted about [001]. A tilt about [010] showed no rotation, as expected from the shape of optical rotation in point group mm2. The absolute indices of the samples were found using X-ray anomalous scattering. The calculations with a dipole-dipole model show that the As4+-ions in RTA correlate to the main structural contribution of the optical rotation, however, there seems to be an even larger intrinsic contribution due to the Ti4+ - ions as a result of the distorted octrahedral co-ordination with oxygen.

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