The structure of liquid mercury

Abstract

X-ray diffraction patterns have been obtained from liquid mercury at −36°, −10° and +27°c in vacuo. All the intensity patterns of the liquid show a departure from simple mixing in that there is a subsidiary maximum on the high-angle side of the main peak, indicating some degree of structure. Each intensity curve can be interpreted as the result of two separate patterns superimposed on one another and resolved only in the neighbourhood of the main peak. The radial distribution analysis of the intensity curves gives the most probable distance of close approach of the atoms as 3·07 Å; a second distance of about 2·85 Å is derived from the observed subsidiary maximum. These distances can be correlated closely with the two shortest distances of the solid allotropes, α and β mercury (3·005 Å and 2·825 Å respectively). This suggests that the cohesive forces in the solid state exist, to some extent at least, in the liquid. The nature of these forces and of the configurations in the liquid can only be a matter for speculation at present.