Number 16 (Story #1), January 10, 1991 by Phillip F. Schewe and Ben Stein IN BALLISTIC ELECTRON EMISSION MICROSCOPY (BEEM) , an elaboration of scanning tunneling microscopy (STM), electrons (with sufficient energy) from the probe behave ballistically and are able to penetrate a sample consisting of a thin metal film and beneath it a thin semiconductor layer. The measured current provides information about atomic details of the metal-semiconductor boundary; this should help in the design of electronic devices. By using an even higher voltage than is needed to image the boundary layer, scientists at Cornell University (Robert A. Buhrman, 607-255-3732) found that they could inscribe lines (8.5 nm wide) in the boundary layer without disturbing the outer surface of the metal layer above. (Science News, Jan. 5.)