FUNDAMENTAL PARAMETERS OF LOW PROBABILITY PROCESSES

H. J. SÁNCHEZ

Conferencia; SARX 2012; 2012

X-ray spectrochemical analysis accuracy relies on several factors. Experimental factors depend on spectrometers, detectors, optics, sources, sample preparation, technique, etc. However basics interactions and theoretical descriptions of the atomic processes involved are key points in the determination, quantification and detection limits of elements. In this respect, fundamental parameters play a significant role in the calculations because of their intrinsic presence in the atomic processes described by the theoretical expressions. Experimental determinations and calculations are reported frequently of cross sections, emission probabilities, binding energies, characteristic energies, etc. etc. The actual precision of fundamental parameters depends on the element, energy range, etc. and is as low as a few percents up to 30% in other cases. Today, more sensitive detectors and powerful x-ray sources allow measuring interactions and processes that cannot be observed with conventional systems. So, low probability processes have to be accounted to bring a more precise description of the physics involved and more accurate outcomes. This work present a succinct description of atomic interactions and the fundamental parameters related, a brief mention of most common low-probability processes and a more detailed explanation three particular atomic effects and their fundamental parameters: Coster-Kronig transitions, double K photoionizations, and resonant Raman scattering. In these three cases, the physics related is explained, the experimental method for determining the physics magnitudes is shown and some applications are described. Keywords: Fundamental Parameters; Low Probability Processes