Parameters Affecting X-Ray Microfluorescence (XRMF) Analysis

Abstract

X-ray Microfluorescence (XRMF) analysis uses a finely collimated beam of X-rays to excite fluorescent radiation in a sample (Nichols & Ryon 1986). Characteristic fluorescent radiation emanating from the small interaction volume element is acquired using an energy dispersive detector placed in close proximity to the sample. The signal from the detector is processed using a computer-based multi-channel analyzer.XRMF imaging is accomplished by translating the sample through the small X-ray beam in a step or continuous raster mode. As the sample is translated, a pixel by pixel X-ray intensity image is formed for each chemical element in the sample. The resulting digitized image information for each element is stored for subsequent processing and/or display. The images, in the form of elemental maps representing identical areas, may be displayed and color coded by element and/or intensity and then overlayed for spatial correlation.The present study of parameters affecting the performance of an X-ray microfluorescence system has shown how such systems use X-ray beams with effective spot sizes less than 100 micrometers to bridge the gap in analytical capabilities between predominately surface micro analytical techniques such as SEM/EDX and bulk analytical methods such as standard XRF analysis. The combination of XRMF spectroscopy with digital imaging allows chemical information to be obtained and mapped from surface layers as well as from layers or structures beneath the sample surface. Simultaneously, it provides valuable high resolution chemical information in a readily interpreted visual form which displays the homogeneity within a given layer or structure. XRMF systems retain the advantages of minimal sample preparation, non-destructive analysis and high sensitivity inherent to XRF methods.

Application of micro-XRF for nuclear materials characterization and problem solving

“…Micro-X-ray fluorescence (MXRF) was first demonstrated in the 1980s (Nichols et al , 1987) and has been in use for ~25 years. In one of the first reported MXRF studies of actinide samples, Schoonover and Havrilla (1999) demonstrated the key benefits of MXRF (and micro-infrared) in determining elemental heterogeneity.…”

Bridging the Micro-to-Macro Gap: A New Application for Micro X-Ray Fluorescence

“…XRF is classically performed with a large area beam (millimeters to centimeters) as a bulk analysis technique. The emergence of capillary X-ray optics, which focus X-ray beams by multiple reflections off the inner surface of a tapered glass capillary or cluster of capillaries, has enabled the production of an X-ray beam focused to a diameter of 100 μm or finer from a modest, laboratory-scale X-ray tube source (Gurker, 1986; Nichols et al, 1987; Carpenter, 1989). Such a beam diameter is useful for mapping on a large spatial scale where the basic pixel step is matched to the beam size (Boehme, 1987; Carpenter & Taylor, 1991).…”

Detection of visible and latent fingerprints by micro-X-ray fluorescence

“…By moving the specimen surface relative to a stationary X-ray beam, a two-dimensional elemental distribution image is collected by monitoring variations in elemental X-ray intensity versus position. These intensity differences correspond to relative differences in the concentration of a given element dispersed across the specimen (Nichols et al , 1987).…”