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| <p>Laboratory: Argonne National Laboratory</p> | |
| <p>Laboratory Organizational Unit: Materials Science Division</p> | |
| <p>Project Title: Surface Analysis by Resonant Ionization of </p> | |
| <p>Sputtered Atoms</p> | |
| <p> Principal Investigators: Michael J. Pellin, W. F. Calaway</p> | |
| <p>There exists an important class of analytical problems that require both sensitivity and discrimination. This class is exemplified by the increasingly stringent demands of the electronic industry for unambiguous quantitative identification of trace impurities in semiconductor materials at high lateral resolution. Recently, particulate analysis, the isotopic and elemental analysis of micron-sized grains, has also begun to occupy the analytical community. The difficulty in these two cases arises from the need to make the measurement before consuming the few atoms of the element of interest while discriminating against the vast excess of bulk atoms. This program has developed instrumentation based on resonant laser photoionization of sputtered atoms capable of measuring as few as 10 atoms of interest even when the analyte is present at levels measured in parts per trillion. Recent improvements to the apparatus allow the analyte to be localized spatially in the sample to 50 nm laterally and a few monolayers in depth. In comparison with commercial large frame Secondary Ion Mass Spectrometers, the ANL developed instrumentation measures with the same precision particles containing 100 times fewer analyte atoms.</p> | |
| <p>Analytical instrumentation capable of elemental and isotopic analysis of extremely small particulates could be of significant use in the area of forensic analysis. When an object is transported it inevitably picks up particulates. These particulates contain an elemental and isotopic signature of their location. Industrial particulates, for instance, are specific to the process that produced them. Sand particles contain a unique isotopic record due to geochemical formation mechanisms. Accurate sample tracing requires high precision measurements. This is complicated by the particle size distribution that peaks for very small particles. Precise trace measurement for small particles is where the ANL instrument excels.</p> | |
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