Number 120 (Story #1), March 26, 1993 by Phillip F. Schewe and Ben Stein|
LIGHT WAVES CAN BE USED AS A LENS to focus a beam of neutral atoms, creating the possibility of a fundamentally new form of submicron lithography. At the APS meeting in Seattle this week, Gregory Timp of AT&T Bell Labs reported on an experiment in which a stream of sodium atoms, cooled to mK temperatures in an "optical molasses" setup and gently steered by the electric fields of an optical standing wave, were deposited on a silicon substrate in a series of closely spaced (less than 300 nm) lines. A comparable grating pattern can be created using transmission electron microscopy, but Timp believes that his line spacings and line widths can be greatly reduced as his technique is further refined. Furthermore, he hopes that with additional focusing he will be able to produce not just well collimated lines but also spots (quantum dots). Sodium atoms are easy to manipulate but are chemically reactive and therefore not suitable for doing lithography, so Timp will try indium atoms next. At the same meeting, Robert Celotta of NIST reported on the laser manipulation of neutral chromium atoms.