Program for Synthesis of Wavelength-Dispersive Electron Probe Spectra
This program allows the synthesis of wavelength-dispersive spectra, using stored experimental spectra, to facilitate the selection of optimal positions for background measurements and assist in the choice of suitable counting strategies for specific analytical situations.
Fuller details are given in:
- S.J.B.Reed and A.Buckley "Virtual WDS". Mikrochim. Acta [Suppl], 13, 479-483, 1996, and
- S.J.B.Reed & A.Buckley. Computer simulation applied to WD analysis. Microscopy and Microanalysis 4 (Supplement 2), 236-237, 1998.
Examples of its application can be found in:
- S.J.B.Reed and A.Buckley "Rare Earth Element determination in minerals by electron probe microanalysis". Mineralogical Magazine, 62, 1-8, 1998.
- A.Buckley and S.J.B.Reed "Spectral interferences in light element analysis". Mikrochimica Acta, 132, 153-155, 2000.
- N.C.Scherrer et al. "Microprobe age dating and REE quantification on monazite". Schweiz. Min. Pet., 80, 93-105, 2000.
- Schimrosczyk. A et al. "Trace element analysis of belite in hardened cement bonded materials using electron microprobe analysis". Eur. J. Mineral. 19, 105-112, 2007
- Pyle,J.M., Spear,F.S., Wark,D.A., Daniel, C.G., Storm, L.C. Contributions to precision and accuracy of monazite microprobe ages American Mineralogist, 90, 547-577, 2005
This program has been developed to run under Microsoft Windows and will run on either WFW, Windows95/98, WindowsNT, Windows 2000, WindowsXP, Windows ME or Win7. A 16 bit version is still available for WFW but the latest version is 32 bit only (i.e. W95/98/2000/NT/XP/ME).
A demonstration version can be downloaded by anonymous FTP. Two tutorial guides are available here:
Application of Virtual WDS to Different Instruments
In principle, the Virtual WDS program is applicable to any type of WD spectrometer. However, the X-ray spectra used in the database were acquired with a particular instrument (Cameca SX50) and this has certain implications for those with other instrument types.
The program can cater for different spectrometer scales - including sine theta and millimetres. Although the Bragg angle range of the Cameca SX50 is 13 to 56 degrees some other spectrometers cover a wider range, especially at the high end. As no experimental data are available, X-ray lines which fall outside the SX50 range cannot be displayed (in practice these are relatively rarely used for analysis).
All WD spectrometers in current use are of fairly similar design but there may be some differences in resolution. However, it appears that these variations are too small to significantly affect the choice of background positions. It is not possible to reproduce the narrower line width obtained with slits. Overlap corrections are more sensitive to line width, but should in any case be determined empirically for each instrument (the main function of Virtual WDS is to warn when this is necessary).
X-ray intensities shown on the screen are inevitably only approximate: apart from instrument-to-instrument variations, they do not take account of sample absorption effects, etc.. Different instruments also use different X-ray detectors; currently no allowance is made for this and the data displayed were recorded using Ar filled counters. However, the relative intensities of lines of similar wavelength should be reasonably correct. The main significance of the absolute intensities is for prediction of statistical precision and detection limits, which are only approximate estimates in any case.
At present the only crystals covered are TAP, PET, LIF and the 45, 60, 100 and 200 Å multilayers (PC0, PC1, PC2, PC3) but others may be added as further data are acquired.
VirtualWDS is marketed by Cambridge Enterprise Ltd.
Fully licensed copies can be obtained from:
Cambridge Enterprise Ltd.,
The Hauser Forum,
3 Charles Babbage Road,
Tel.: +44 (1223) 760339 Fax.: +44 (1223) 764888