Bragg scattering of 412 keV gamma‐radiation: A new technique for studying the wavefunctions of the inner electrons in heavy atoms

Abstract

For the first time absolute integrated intensities of Bragg reflections of gold have been measured up to values of sin θ/λ∼2.7 Å⁻¹ using the technique of gamma-ray diffractometry (Schneider 1974). The accuracy obtained for the reflection 0 0 16, for example, is of the order of 2%. On the basis of these first results, we discuss the possibility of measuring the atomic form factor f° for Au and comparing the experimental values with the results of various relativistic calculations. These theoretical form factors differ by about 5% for sin θ/λ∼2, that is by about 10% in the integrated Bragg intensity R _m. Before f° can be deduced from R _m, the effect of the thermal vibrations on the measured intensities must be taken into account and, in addition, one must justify the validity of the form factor approximation. At high momentum transfers both questions are interesting in themselves, but from the available experimental data we conclude that for momentum transfers l.5≲sin θ/λ ∼ 2 Å⁻¹ it should be possible to separate these problems from the determination of the atomic form factor itself.