A New Technique for Standardless Analysis by EPMA-TWIX

Angle-resolved electron probe microanalysis revisited

“…The present investigation has been previously undertaken with a dedicated electron microprobe [9] as well as with a SEM that has an EDS detector [10]. As intuitively expected and also pointed out by Völkerer et al [10], the main experimental problem is the sample positioning in the instrument.…”

“…It also be kept in mind that the goal of present calculations is to evaluate the trends of the functions f(χ) and of the K ratios when θ is varied. The function Φ(z) appears in the numerator and in the denominator of fractions defining f(χ) and K -see below-so that the errors made on Φ(z) partly compensate each others: a fact also pointed out by Völkerer et al [10]. …”

“…This type of investigation has been performed by Völkerer et al to illustrate a new technique for standardless analysis called EPMA-TWIX [10]. With an incident angle of i~20°for a detector angle of d= 55°, their operating conditions were not optimized so that the take-off angle was successively equals to θ=15°and to θ=55°when they performed two measurements by a horizontal rotation ω of 180°.…”

“…In fact only two papers have been devoted to this topic: that of Gennai et al, 1971, who used a 'variable take-off angle method' to measure the absorption factor, f(χ), in a dedicated electron microprobe, [9] and ref. incl., and that of Völkerer et al, 1998, who rotated a tilted sample round 180°in a Scanning Electron Microscope (SEM) to characterize some overlayers on homogeneous substrates [10]. The key point of these two approaches is that the characteristic x-ray line intensities, I(θ), are collected at variable take-off angles θ but keeping unchanged the excitation conditions and the detector's position.…”

“…Gennai et al [9] and one hand, Völkerer et al [10] have overcome this difficulty by setting the inclined sample on a rotating sample holder with a rotation axis co-axial to the incident beam:…”