Interference and Radial Distribution Functions of Liquid Copper, Silver, Tin, and Mercury

The x-ray scattering from liquid copper, silver, tin, and mercury was measured at temperatures of 1125°C, 1050°C, 335°C, and 28°C, respectively, from the open surface of horizontal samples using a focusing theta-theta diffractometer, quartz crystal monochromator positioned in the diffracted beam, scintillation detector, and pulse height discriminator. The effect on the measured intensities of the positioning of the sample with respect to the diffractometer axis and the meniscus of the liquid were considered. Calibration of the primary beam intensity by measurements on liquid mercury provided an alternate check of the standard normalization procedures for copper, silver, and tin. After calculation of the interference functions, atomic and radial distribution functions were evaluated from which interatomic distances and coordination numbers were obtained. The interatomic distances in the liquid were in good agreement with the GOLDSCHMIDT diameters of the respective elements.