X-ray spectromicroscopy with a zone plate generated microprobe

The scanning photoelectron microscope at the National Synchrotron Light Source (NSLS) has recently recorded micrographs with a resolution below half a micron. To demonstrate elemental and chemical sensitivity at the submicron level, an artificial structure consisting of Al and SiO2 lines on a boron-doped silicon substrate was examined. Al 2p and Si 2p primary photoelectrons as well as O KVV Auger electrons were used for image formation. Contrast reversal between the the Si and SiO2 areas was observed in images formed from Si 2p and oxide-shifted Si 2p photoelectrons. The soft x-ray undulator at the NSLS provides coherent illumination of a zone plate to produce the microprobe. The sample is mechanically scanned through the beam allowing the formation of images from photoelectrons detected by a single-pass cylindrical mirror analyzer, or a more complete spectroscopic examination of a selected area of the sample.