PERFORMANCE OF TXRF and GI-XRF ANALYSES - Total-Reflection X-Ray Fluorescence Analysis and Related Methods - page 205

CHAPTER

4
PERFORMANCEOFTXRFandGI-XRFANALYSES

4.1PreparationsforMeasurement 207
4.1.1 Cleaning Procedures 207
4.1.2 Preparation of Samples 211
4.1.3 Presentation of a Specimen 215
4.2AcquisitionofSpectra 222
4.2.1 The Setup for Excitation with X-Ray Tubes 222
4.2.2 Excitation by Synchrotron Radiation 225
4.2.3 Recording the Spectrograms 226
4.3QualitativeAnalysis 228
4.3.1 Shortcomings of Spectra 228
4.3.2 Unambiguous Element Detection 236
4.3.3 Fingerprint Analysis 237
4.4QuantitativeMicro-andTraceAnalyses 238
4.4.1 Prerequisites for Quantification 240
4.4.2 Quantification by Internal Standardization 244
4.4.3 Conditions and Limitations 248
4.5QuantitativeSurfaceandThin-LayerAnalysesbyTXRF 257
4.5.1 Distinguishing Between Types of Contamination 257
4.5.2 Characterization of Thin Layers by TXRF 262
4.6QuantitativeSurfaceandThin-LayerAnalysesbyGI-XRF 267
4.6.1 Recording Angle-Dependent Intensity Profiles 268

4.6.2 Considering the Footprint Effect 270

4.6.3 Regarding the Coherence Length 272

4.6.4 Depth Profiling at Grazing Incidence 274

4.6.5 Including the Surface Roughness 283

An analytical strategy has to be based on the prerequisites of the method to be
applied. Above all, total reflection X-ray fluorescence (TXRF) is restricted to
small sample amounts. Only micrograms of a solid material and less than 100 μ l
of a liquid can be analyzed at one time. Consequently, TXRF is a method of
microanalysis, as is defined by the International Union of Pure and Applied
Chemistry (IUPAC) [1], and samples can seldom be analyzed as received.