X-Ray Fluorescence Spectroscopy for Laboratory Applications. Jörg Flock

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Preface

      The discovery of X-rays by Wilhelm Conrad Röntgen dates back to nearly 125 years. Despite their “age,” the research and discoveries that have been made in the past and today make X-rays one of the most powerful analytical tools available today. The discovery of this part of the electromagnetic spectrum has seen many applications. First, used for medical purposes by Röntgen himself, who found that the newly discovered rays can penetrate and at the same time can be absorbed by different types of matter. Therefore, it was now possible to image the human body. Later, Max von Laue showed that they are a higher-frequency part of the electromagnetic spectrum where natural light is also a part of. This led to his work on diffraction of X-rays, which to this day is used to investigate the crystalline and amorphous structure of solids. Finally, Moseley found that every element emitted characteristic X-ray radiation that can be used to determine the qualitative and quantitative elemental composition of materials of different types. This is the application that is most interesting for us – the spectroscopists.

      X-ray fluorescence spectroscopy has now developed into an analytical technique that, due to its robustness and flexibility, can be used in almost all scientific areas, in research, and above all in quality control in industrial production. The technique has become so powerful because of its ability to analyze many different material types, having a wide range of elements and concentrations. The sample preparation is mostly simple or even not required, therefore making it possible to fully automate the entire analysis process.

      Even when one has many years of experience with the method, specific expertise is still required to achieve reliable results, especially since the applications for X-ray fluorescence spectrometry have been significantly expanded in recent years due to new components being developed and becoming commercially available for X-ray spectrometers. Examples of such are X-ray optics, new types of detectors, and the availability of powerful computing technique and software solutions.

A combination of theoretical knowledge and practical know-how about the materials 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

About the Authors

      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.

1 Introduction

      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 СКАЧАТЬ