electron spectroscopy (AES) normally uses an electron beam as the probe. Confocal microscopy X-ray fluorescence imaging is a newer technique that allows control over depth, in addition to horizontal and vertical aiming, for example, when analysing buried layers in a painting. Instrument qualification A 2001 review, addresses the application of portable instrumentation from QA/QC perspectives. It provides a guide to the development of a set of SOPs if regulatory compliance guidelines are not available. See also , resonant fluorescence of gamma rays Notes References Beckhoff, B., Kanngießer, B., Langhoff, N., Wedell, R., Wolff, H., Handbook of Practical X-Ray Fluorescence Analysis, Springer, 2006, Bertin, E. P., Principles and Practice of X-ray Spectrometric Analysis, Kluwer Academic / Plenum Publishers, Buhrke, V. E., Jenkins, R., Smith, D. K., A Practical Guide for the Preparation of Specimens for XRF and XRD Analysis, Wiley, 1998, Jenkins, R., X-ray Fluorescence Spectrometry, Wiley, Jenkins, R., De Vries, J. L., Practical X-ray Spectrometry, Springer-Verlag, 1973, Jenkins, R., R.W. Gould, R. W., Gedcke, D., Quantitative X-ray Spectrometry, Marcel Dekker, electronic-book electronic- Van Grieken, R. E., Markowicz, A. A., Handbook of X-Ray Spectrometry 2nd ed.; Marcel Dekker Inc.: New York, 2002; Vol. 29; External links Atomic physics Molecular physics X-ray spectroscopy Fluoro Scientific techniques Fluorescence