Experimental Determination of f″ for Ga and In From Bijvoet Ratio

The imaginary components of the anomalous dispersion correction terms for the heavy atoms gallium and indium, evcaluated from a systematic and precise experimetal measurement of the Bijvoet ratios for the spherically ground single crystals of GaP and InP, are reported. The procedure used is based on the work of Engel and Sturm who refined the crystal structures involving light atoms using anomalous scattering and employed the measured structure factors to evaluate the f″ values of the heavy atoms. In the present work, instead of refining the crystal structure, the structure factors are obtained using a refinement program. The experimentally evaluated f″ values are in very close agreement with the reported theoretical values.