Abstract

The focusing of a modestly energetic pulsed laser beam (E ≳ 10 mJ) can lead to a breakdown plasma which may be used for qualitative and quantitative spectrochemistry. Although the precision of the method is poorer than that of conventional spectrochemical techniques, the method has distinct advantage in certain circumstances. (1) The plasma can be generated without electrodes, hence non-invasive (but destructive) analysis is possible in hostile environments. (2) Being an emission technique, simultaneous multi-element analysis is possible. (3) The plasma can be made almost arbitrarily small, allowing microanalysis of samples. (4) In contrast to common laser microprobe techniques, auxiliary analysis is not required, simplifying the instrument package and reducing the cost. (5) A variety of sample forms can be interrogated, conducting or nonconducting solids, as well as liquids and gases. (6) Preparative chemistry of the sample is not required, allowing truly real-time analysis. The latter fact is a two-edged sword. Real samples are often inhomogeneous, and their sampling leads to reduced precision. The method is limited to elemental analysis, because the plasma dissociates molecules. In general the precision of the results is not high, although detection limits can be quite good, as indicated below. The applications for this technique will not be those amenable to conventional laboratory spectro-chemistry, they will be the ingenious ideas of the frustrated analyst. The review given here cannot be all-inclusive. I have chosen examples which indicate the breadth of applications, and obviously ones with which I am familiar. The early history of laser plasma spectrochemistry is reviewed by Laqua (1).

© 1985 Optical Society of America