Although the variety of systems studied with synchrotron radiation is growing daily, it is increasingly common for CHESS visitors to share one need: they wish to study smaller specimens than ever before - or they wish to examine very small regions of larger samples. One might be the biochemist who can only grow a macromolecular crystal to 20 microns in size, another a material scientist who needs to understand crystallite formation in a 0.25 micron wire built into an integrated circuit, or a third might be a biophysicist who wants to understand why the dragline silk of a spider is one of the strongest materials (by weight) on earth; another may be a geologist who needs to study the salt content inside a fluid bubble trapped in an ancient rock.

Growing from these needs, there is considerable interest in making hard X-ray microbeams that can be used to probe the tiniest features in samples. Among the techniques being used to create microbeams, pioneering work by a CHESS group lead by Staff Scientist Don Bilderback has proven that tapered glass capillary pipettes can be used to "funnel" or concentrate X-rays beams. By heating and stretching hollow glass tubing, they have demonstrated that X-ray beams can be condensed to spots as small as 500 Angstroms.

Using these tiny beams to illuminate a very small region of a specimen, scientists can study minute features and obtain very high spatial resolution. The figure at right demonstrates a microbeam measurement of the structure of a high-performance optical fiber used by the telecommunications industry. Tiny beams are also being to being used to study the internal features of 0.18 micron Aluminum wires on integrated circuits, for example, where the growth of grain boundaries and electromigration are known to cause device failure.