Specimen damage considerations in biological microprobe analysis.

In many biological materials radiation damage limits the resolution of the microanalytical measurement. To provide some perspective regarding the relative merits of different experimental arrangements, the dose to the specimen may be calculated using a simple model. While electron and proton probe X-ray microanalysis are found to involve heavy doses to the specimen, X-ray fluorescence, performed with a polarized, monochromatic X-ray probe, is the least destructive for the analysis of medium to heavy elements. For light elements (Z less than or equal to 20), electron energy loss spectroscopy or X-ray absorption microanalysis involve the lowest dose in most applications. Other advantages and limitations of the various techniques are also summarized.