Effect of atomic parameters on L-shell X-ray production cross-sections by proton impact with energies below 1 MeV J. Miranda a, * , C. Romo-Kr € oger b , M. Lugo-Licona a a Instituto de F  ısica, Universidad Nacional Aut onoma de M exico, A.P. 20-364, 01000 Mexico, D.F., Mexico b Universidad de Tarapac a, Casilla 592, Arica, Chile Abstract The role of the atomic parameters involved in the calculation of L-shell X-ray production cross-sections due to the impact of protons with energies below 1 MeV is discussed. Three data sets of emission rates and two tables of fluo- rescence yields and Coster–Kronig probabilities are compared, based on the whole body of published experimental measurements of L X-ray lines and theoretical predictions of the ECPSSR model. It is found that one specific set of emission rates together with one specific set of fluorescence yields and Coster–Kronig factors provide the best results for X-ray lines involving L 2 and L 3 subshell transitions. For lines based on L 1 subshell transitions, however, that set of emission rates is not the best to predict the cross-sections. It is noted, however, that more reliable measurements of Coster–Kronig probabilities are necessary, in spite of the availability of refined experimental methods. Ó 2002 Elsevier Science B.V. All rights reserved. PACS: 32.80.Hd; 33.50.Hv; 34.50.Dy Keywords: X-ray emission; Fluorescence yields; Emission rates; Coster–Kronig probabilities 1. Introduction The most important physical quantity involved in particle induced X-ray emission (PIXE) is un- doubtedly the X-ray production cross-section after the ion beam impacts on the target atoms. The interest is not limited to the development of ap- plications, but also from the basic physics point of view [1]. Usually, PIXE is applied using protons with energies between 2 and 3 MeV. The emission of K X-rays is well understood, with tables of ‘‘reference’’ cross-sections already published [2]. However, as discussed in a previous work [3], the situation for L and M X-rays, and in particular for proton energies below 1 MeV, is still unclear, as the experimental data show significant differences with theory, which can not be attributed to the models only. Moreover, quantitative analyses us- ing PIXE present difficulties when using L X-rays [4]. There are important atomic parameters in- volved in the calculation of X-ray production cross- sections from ionization cross-sections, namely fluorescence yields and Coster–Kronig transition probabilities. Several calculations and measure- ments of these parameters have been performed to date; unfortunately, there has not been any recent overall evaluation of them, in spite of the effort by Nuclear Instruments and Methods in Physics Research B 189 (2002) 21–26 www.elsevier.com/locate/nimb * Corresponding author. Tel.: +52-55-5622-5005/5622-5073; fax: +52-55-5622-5009. E-mail address: miranda@fisica.unam.mx (J. Miranda). 0168-583X/02/$ - see front matter Ó 2002 Elsevier Science B.V. All rights reserved. PII:S0168-583X(01)00988-0