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The invariant phases of large numbers of germanium triplets, consisting of one forbidden and two permitted reflections, have been determined experimentally. The forbidden reflections include members of the forms {200}, {222}, {420} and {442}. Phase effects in triplets containing members of the ultra-weak (forbidden) {622} and {640} were detected but were too weak to provide reliable phase indications. The phases of all triplets which include a forbidden reflection and the 
reflection are observed to be negative. The phases of individual forbidden reflections, whose indices are described as summing to (4n - 2), are equal to (-1)n. The imaginary part of the dispersion correction to the atomic form factors is relatively large (0.89 for Cu Kα1 radiation): it makes significant contributions to the structure factors and the phases of the vanishingly weak forbidden reflections.
reflection are observed to be negative. The phases of individual forbidden reflections, whose indices are described as summing to (4n - 2), are equal to (-1)n. The imaginary part of the dispersion correction to the atomic form factors is relatively large (0.89 for Cu Kα1 radiation): it makes significant contributions to the structure factors and the phases of the vanishingly weak forbidden reflections.
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