AES AND XPS MEASUREMENTS - REDUCING THE UNCERTAINTY AND IMPROVING THEACCURACY

In this brief review we consider recent work from NPL to reduce both s ystematic and random uncertainties in quantitative AES and XPS. The ma jor problem causing systematic uncertainty is the use of sensitivity f actors which have been derived for one instrument being applied to a s econd instrument when the transmission functions of neither have been determined. Here we show how transmission functions may be established in both YPS and AES instruments and, in the latter case, for both the direct and differential mode. The calibration in the differential mod e overcomes problems associated with internal scattering which is stro ng in certain instruments. The effects of random uncertainties may be reduced two ways, (i) by optimal processing of the data to make use of all the information and (ii) by using the most appropriate computatio nal route.