Proton microprobe

There are two principal sources of reliable partitioning data for any trace element glassy volcanic rocks and high temperature experiments. For the reasons outlined above, both sources rely on analytical techniques with high spatial resolution. Typically these are microbeam techniques, such as electron-microprobe (EMPA), laser ablation ICP-MS, ion-microprobe secondary ion mass spectrometry (SIMS) or proton-induced X-ray emission (PIXE). 

Grime, G.W. (1999) Proton microprobe (methods and background) in Encyclopaedia of Spectroscopy and Spectrometry, J.C. Lindon, G.E. Tranter J.L. Holmes, Ed. Academic Press, Chichester, pp. 1901-1905. 

Figure 3. Starting with the binocular microscope, discriminatory power increases in a counterclockwise direction, as indicated by the circular background. Variations in flowline width reflect the differential sampling capabilities of the techniques. Special petrological techniques include X-ray diffraction, electron and proton microprobe, staining, and heavy mineral separation.

Malmqvist KG. Proton microprobe analysis in biology. Scanning Electron Microsc 1986 IB 821-845. 

Janssens, K., Aerts, A., Yincze, L., et al. (1996). Corrosion phenomena in electron, proton and synchrotron X-ray microprobe analysis of Roman glass from Qumran, Jordan. Nuclear Instruments and Methods B 109-110 690-695. 

Some of the disadvantages of the electron-probe method may be overcome, as in other methods, by the use of complementary techniques. Such techniques can complete the results obtained by electron microprobe. For instance, the introduction of a proton microprobe [39], which is much more sensitive (by two orders of magnitude) than the electron microprobe, and may be used with very good results in geochemical and cosmochemical studies. 

NMR spectra heteronuclear gold cluster compounds, 39 345-348 Phalaris canariensis esophageal cancer, 36 144-145 scanning proton microprobe, 36 149 structural motifs of silicas, 36 146 Pharmaceuticals, 18 177 Phase transitions, in chalcogenide halide compounds, 23 332, 408, 412 [PhCHjMejNAlHjlj, 41 225-226 [(PhCH2)jNLi]3 molecular structure, 37 94, 96 in solution, 37 107-108... 

Cahill, T. A, Proton Microprobes and Particle-Induced X-Ray Analytical Systems, Annu. Rev. Nucl. Part. Sci., 30, 211-252 (1980). 

An important variant on PIXE is micro-PIXE. By using a proton beam whose spatial dimension is 0.5 pm (rather than the usual 10 mm), one can determine the trace-element content of a small portion of the sample, giving one a trace-element microscope. This application is important in probing samples of medical interest. A related technique is used in the electron microprobe where the ionization is caused by electron impact. 

Morrison et al. (1981) have used the proton microprobe to map K, Ca, Mn and Co by scanning across a leaf. The instrument is similar to the electron microprobe, but has a sensitivity of the order of 1 -10 pg g 1. It can also be operated in air instead of vacuum, these two differences rendering the method very suitable for plant analyses. The results showed that in the region of potassium deficiency there were elevated levels of calcium and cobalt. 

Forslind, B. et al., Quantitative correlative proton and electron microprobe analysis of biological... 

G.E. Coote, R.W. Gauldie, W.J. Trompetter, I.C. Vickridge, A. Markwitz, Twenty years of proton microprobe research in biominerals a tribute to Graeme Ernest Coote, 1935-1997, Nucl. Instr. Meth. B158 (1999) 1-5. 

G.W. Grime, M.H. Abraham, M.A. Marsh, The new external beam facility of the Oxford scanning proton microprobe, Nucl. Instr. Meth. B181 (2001) 66-70. 

A routine sample for proton NMR on a 300 MHz instrument consists of about 10 mg of the compound in about 0.5 ml of solvent in a 5-mm o.d. glass tube. Microprobes that accept a 1.0 mm, 2.5 mm, or 3 mm o.d. tube are available and provide higher sensitivity. Under favorable conditions, it is possible to obtain a spectrum on 100 ng of a compound of modest molecular weight in a 1.0 mm microtube (volume 5 pi) on a 600 MHz instrument. 

Two-dimensional NMR provides powerful tecniques to aid interpretation, but the starting point is a simple, one-dimensional proton NMR spectrum, with careful integration to ascertain the relative numbers of protons in different lines or multiplets. In some instances one or two good 1H NMR spectra may be sufficient to solve the problem with little expenditure of instrument time. In other instances, where only minute amounts of sample are available, it may not be feasible to obtain any NMR data other than a simple H spectrum. However, as we pointed out in Chapter 3, with modern instrumentation and microprobes, it is usually possible to use indirect detection methods to obtain correlations with less sensitive nuclei, such as 13C and 15N, even with quite small amounts of sample. 

O Reilly S. Y., Griffin W. L., and Ryan C. G. (1991) Residence of trace elements in metasomatized spinel Iherzolite xenohths a proton-microprobe study. Contrib. Mineral. Petrol. 109, 98-113. 

Ewart A. and Griffin W. L. (1994) Application of proton-microprobe data to trace-element partitioning in volcanic rocks. Chem. Geol. 117, 251—284. 

The application of the Oxford scanning proton microprobe to these studies was of particular importance in the monitoring of trace ele-... 

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