eyond the advent of commercially marketed magnetoresistant and superconducting materials, next up for the electronics industry in this country is the age of nanotechnology. The word "nanotechnology" comes from nanometer, which means one billionth of a meter (about 25 millionths of an inch or 10 angstroms). Proponents of nanotechnology are envisioning machines that are roughly equivalent in size to a protein molecule. Experts agree that the arrival of the nanotechnology age will hinge upon the ability of researchers to characterize and control the atomic structure of surfaces and interfaces. This ability received a big boost in 1995 with the commissioning at the ALS of the most extensive surface science experimental station ever to be linked to the beamline of a synchrotron-radiation particle accelerator. The surface science experimental station is located on ALS beamline 9.3.2, a bend-magnet beamline that produces photons between 30 and 1500 electron volts in energy. This energy range permits the study of both the inner "core" as well as the outer "valence" electrons of all elements. The station is designed specifically for photoelectron spectroscopy and photoelectron diffraction-collectively known as PES/PED-two of the most powerful techniques known to science for the study of solid surfaces.

At this new experimental station, Berkeley Lab researchers working with users from outside the Laboratory will be able to obtain detailed information on what types of atoms are present on a surface, how many there are of each type, and how they are arranged in space. It will also be possible to identify the chemical or magnetic states of these atoms, and in some cases to produce holographic images. The information learned will provide U.S. chip manufacturers with a big advantage in their efforts to fabricate nanoscale semiconductor and magnetic storage devices.

Nanoscale devices are so small they become two- or even one-dimensional objects-essentially nothing but surfaces and interfaces. Another critical factor in bringing nanotechnology to fruition will be a better understanding of how electrons move through materials that are less than three-dimensional. Berkeley Lab scientists studying the dynamics of electrons at surfaces made strides recently with the solution of a long-standing problem concerning the effect on the motions of electrons near a metal surface when that surface is coated with thin films of an insulating material. Making good use of new lasers that can deliver tunable pulses of light only 100 femtoseconds in duration (one femtosecond is a millionth of a billionth of a second), the scientists have been able to follow electrons as they move back and forth across the interface between a metal surface and an insulating film of molecules. They've also been able to vary the thickness of the insulating film by a single layer of molecules at a time in order to study the effects on electron movements as devices increase from two dimensions to three. What made this research possible in addition to femtosecond lasers was a technique called "two-photon photoemission" and an unusual electron time-of-flight detection scheme that gives unprecedented sensitivity and highly precise energy measurements.

Berkeley Lab scientists this past year also successfully demonstrated the first ever catalysis on a nanometer scale. Working with UC Berkeley researchers, they modified an Atomic Force Microscope so that it functioned like an ultrafine-point pen for catalytic calligraphy. With this unique new tool, they were able to create a reaction that changed the chemical composition of the surface of a material one molecule at a time.

This unprecedented demonstration of molecular synthesis on such a tiny scale represents a promising step towards the development of nano-fabrication. One key to its success was the combination of atomic force microscopy with a technique from organic chemistry called molecular self-assembly. Another key was performing the research at a multiprogram national laboratory where chemists and physicists can and do work together.

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