Net atomic charges, electric moments, and sign and magnitude of optical rotatory power in α-TeO2 at 296 K

Optical activity is determined from a point charge model in one enantiomorph of a chiral and semiconducting α-TeO2 crystal. Net atomic charges of Te and O atoms are iterated and electric moments derived. Second electric moments in the principal axis directions are calculated and their ratio is fitted by comparison with the corresponding ratio of the optical refraction indices. The components of the axial vectors are calculated and converted to the gyration tensor components. The optical rotatory power in the positive direction of the optic axis is determined, and the sense of optical rotation is defined from transformations of polar vectors of first rank of the TeO2 groups and visually confirmed in both enantiomorphs.

Temperature-dependent optical rotatory power in the presence of birefringence of KTA and KTP crystals by the high-accuracy universal polarimeter method at 632.8 nm wavelength

Temperature-dependent simultaneous measurement of birefringence and optical rotatory power (ORP) for orthorhombic crystals of potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) has been achieved by using the high-accuracy universal polarimeter method at 632.8 nm wavelength. The birefringence and ORP changes along the (110) planes for KTA and KTP crystals were found to have a nearly parabolic form for the temperature range 297–493 K. The thermal variation coefficients were found to be 0.9 (5) × 10−5 K−1and 5.6 (3) × 10−8 K−2for KTA and 0.9 (5) × 10−5K−1and 5.7 (3) × 10−8 K−2for KTP. The ORPs at 297 K were found to be 20.0 (20) and 20.5 (15)° mm−1for KTA and KTP, respectively. The thermal variation coefficients of the ORP were found to be 1.8 (2) × 10−3° mm−1 K−1and 1.1 (1) × 10–5° mm−1 K−2for KTA and 1.9 (2) × 10−3° mm−1 K−1and 1.2 (1) × 10−5° mm−1 K−2for KTP.

Optical Activity of Langatate Crystals

A calculation technique based on the polarizability theory for optical activity (OA) is applied to derive optical rotatory power (ORP) for the La3Ga5.5Ta0.5O14 (LGT). Dispersions of both the ordinary and extraordinary refractive indices and the ORP are calculated. A comparison of the observed and calculated OA parameters confirms validity of our theoretical calculations.