Number 292 (Story #3), October 23, 1996 by Phillip F. Schewe and Ben Stein HELIUM DROPLETS AS A NANOSCALE CRYOSTAT . The study of tiny clusters of metal atoms (clusters represent a form of matter poised between the atomic and bulk worlds) is complicated by surrounding factors. If placed on a solid substrate, the clusters (most of whose atoms are at or near a surface) take on some of the properties of their support medium. By contrast, clusters in a beam are not contaminated by a surface but exist in a relatively hot environment. Scientists at the Max Planck Institute in Gottingen (Germany) get around these problems by embedding clusters (of silver, indium, and europium) in droplets of helium. The clusters (with as few as 100 atoms) are stable and at a precisely defined temperature of 0.37 K, making possible high resolution spectroscopy and perhaps the study of superconductivity in cold metal clusters. (A. Bartelt et al., Phys Rev Lett, 21 Oct.)