X-Ray Fluorescence Spectroscopy for Laboratory Applications - Jörg Flock

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to be examined, the best practices for sample preparation, and the most suitable measuring instrument at optimal measurement conditions is required to make the most precise and true analysis results. The intention of this book is to summarize the experiences of the analytical community working with X-ray fluorescence. For many years this community has convened at global annual user meetings and conferences for X-ray fluorescence spectrometry, covering all types of applications of X-ray spectroscopy. The work presented at these meetings shares new developments in the field of device technology and provides information on the analytical capabilities of X-ray fluorescence for known applications, for instance, in the analysis of metallurgical or mineralogical samples. Interesting new applications are presented as well. These experiences are the basis of this book in which we tried to summarize but also to preserve this knowledge.

      The book is addressed to current and future users of X-ray fluorescence analysis. It strives to provide suggestions and examples on how to use X-ray fluorescence and what kind of results can be expected, as well as advice on suitable preparation techniques and measurement conditions. Accordingly, in addition to the method-specific basics, the book contains information about the essential preparation techniques and a variety of material-specific applications that can serve as the basis for your own current and future measurement concepts.

      Many inspiring discussions and joint projects with numerous users and instrument manufacturers have been included in this book. The authors want to especially thank Prof. A. Janßen, Ms.Sc. S. Hanning and many other colleagues not mentioned here for their support of this work. Our special acknowledgement goes to Dr. A. von Bohlen, he not only supported the project by a lot of discussions but also provided our work with elaborated information about conditions and applications for total reflection X-ray spectrometry.

      Michael Haller dedicates his work in this book to the late Dr. Volker Röβiger. Friend, mentor, and true Renaissance man, his enthusiasm and kindness were an inspiration to all who had the privilege to know him.

      Finally, thanks to the publisher Wiley-VCH for their support and smooth completion of this project.

      We hope that this book will inspire and fascinate all readers using X-rays as an analytical tool.

      February 2020

      Michael Haschke, Jörg Flock, Michael Haller Eggersdorf, Schwerte and Middletown

      Dr. Michael Haschke has worked for more than 35 years in several companies in the field of product management for the development of new products and the market introduction of new methods in X-ray fluorescence. These were mainly instruments in the field of energy-dispersive spectroscopy. During the market introduction it was every time necessary to deal with competitional element analysis methods but also with the new applications. He, therefore, has both knowledge in the field of X-ray fluorescence and analysis method and for the wide range of applications for X-ray fluorescence.

      Dr. Jörg Flock was for many years the head of the central laboratory of ThyssenKrupp Steel AG and therefore familiar with several analytical methods, in particular with X-ray fluorescence spectroscopy. He has a lot of practical knowledge for the analysis of various sample qualities.

      Michael Haller, M.S., has been using X-rays as an analytical tool for over 30 years, first in X-ray crystallography and then later in the development and application of polycapillary X-ray optics. During the majority of his career, he has developed new applications for coating thickness instruments in industrial process control. In 2018 he became co-owner of CrossRoads Scientific, a company specializing in the development of analytical X-ray software.

      X-ray spectrometry has been known as a method for element analyses for more than 70 years and can be regarded as a routine method since the 1960s. This means that there is a broad range of instruments available, and numerous analytical tasks are carried out routinely by X-ray fluorescence (XRF) analysis. For example, XRF is used for the characterization of metallic or geological materials or for analyses of solid or liquid fuels despite the fact that other elemental analytical methods have been developed and are readily available for these applications. Among them are optical emission spectrometry with excitation both by sparks and by inductively coupled plasmas and mass spectrometry. The high importance of using XRF is due to the fact that one can achieve very high precision over a wide concentration range. XRF also requires little effort with sample preparation and the method can be automated.

      Especially in the last 15–20 years, XRF has experienced a new boom mainly because the technology has further developed, and new fields of applications could be opened up. These include, among others, the analysis of layered materials and high-resolution position-sensitive analysis. This was made possible by the availability of new components for X-ray spectrometers.

      The development of high-resolution energy-dispersive detectors with good count rate capability now allows precision measurements also with energy-dispersive spectrometers. The simultaneous detection of a wide energy range over a large solid angle made possible with these detectors allows not only short measuring times but also special excitation geometries. It is therefore now possible to achieve higher sensitivities in the detection of traces; further, the fluorescence radiation of small surface areas can be detected with sufficient intensity.

      The development of various X-ray optics allows shaping of the primary X-ray beam and thus the concentration of high excitation intensity on small sample surfaces; this development was the key to opening up new applications in the field for a spatially resolved analysis.

      These developments have significantly expanded the range of applications of XRF analysis.

      These improvements have been particularly important because X-rays strongly interact with the sample matrix, which requires complex correction procedures. Nevertheless, in contrast to other analytical methods, the physics of these interactions is very well understood and can be exactly modeled mathematically. Consequently, in principle, standard-less analysis is possible, which again requires a high computing effort.

      As a result of these developments, new methodical possibilities for XRF emerged, combined with an expansion of their field of applications. For this reason, it seems to be meaningful to carry out an up-to-date compilation of the applications currently being processed by XRF, in combination with a discussion of both the necessary sample preparation and instrument-related efforts and the achievable analytical performance. There are several very good books available, which however, due to their date of publication, have not been able to take into account the developments of the last 15–20 years (Erhardt 1989; Hahn-Weinheimer et al. 2012) or they do not adequately address frequently used routine applications, in particular in industrial analyses (Beckhoff et al. 2006; van Grieken and Markowicz 2002).

      The goal of this book is to focus on the practical aspects of the various applications of XRF. This leads to the discussion of the requirements necessary for the analysis of the very different sample qualities, such as the type of sample preparation, the available measurement technique or the required calibration

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