X-ray diffraction study on amorphous gallium

Amorphous films of some μm in thickness, prepared by low temperature condensation in an ultra-high vacuum onto liquid helium cooled substrates, have been studied in situ by using an X-ray diffractometer operating in a symmetrical reflection mode. The structure factor of gallium has been obtained over the wavevector range 1.3 to 16.1 Å⁻ by means of two wavelengths, Cr_K and Mo_K, monochromatized by balanced filters. The average number of nearest neighbours deduced from the well-resolved first maximum in the radial distribution function is equal to 9.3 atoms. The results are compared to those previously found by electron diffraction measurements on thin films and also to the structure of supercooled liquid.