Microbeam

Trebbia P. Quantitative elemental mapping of X-ray radiographs by ffactorial analysis of correspondence. Proc 5 th Eur.workshop on modern developments and applications in microbeam analysis, Torquay UK,149-173, 1997... 

This overview covers the major teclnhques used in materials analysis with MeV ion beams Rutherford backscattering, chaimelling, resonance scattering, forward recoil scattering, PIXE and microbeams. We have not covered nuclear reaction analysis (NRA), because it applies to special incident-ion-target-atom combinations and is a topic of its own [1, 2]. 

Watt F, Grime G W and Fliiger A Principles and Applications of High-Energy Ion Microbeams (Bristoi institute of Physios)... 

T. Dingle and B. W. Griffiths.In Microbeam Analysis-1985 Q. T. Armstrong, ed.) San Francisco Press, San Francisco, 315, 1985. Contains examples of quantitative anal)n ical applications of LIMS. 

L. Van Vaeck and R. Gijbels. in Microbeam Analysis-1989 (P. E. Russell, ed.) San Francisco Press, San Francisco, xvii, 1989. A synopsis of laser-based mass spectrometry anal)n ical techniques. 

NRA can be highly sensitive, with typical detection limits of 10 atoms/cm, depending on the reaction involved. Depth resolutions typically range from a few nm to tens of nm, and lateral resolutions down to a few m can be achieved with microbeams. 

With the use of a microbeam, lateral resolution with NRA on the order of several pm is possible. Flowever, because of the small beam currents obtainable with microbeam systems, sensitivity is limited and reactions with relatively large cross sections are most useful. Only a few laboratories perform microbeam measurements. 

The maximum sample size is limited only by the design of the sample chamber. Typically, samples up to several cm in diameter can be accommodated. A diameter of a few mm is generally the lower limit because high-energy ion beams focused through standard beam optics are on the order of a few mm in diameter however, microbeam setups permit the use of samples an order of magnitude smaller. 

NRA is an effective technique for measuring depth profiles of light elements in solids. Its sensitivity and isotope-selective character make it ideal for isotopic tracer experiments. NRA is also capable of profiling hydrogen, which can be characterized by only a few other analytical techniques. Future prospects include further application of the technique in a wider range of fields, three-dimensional mapping with microbeams, and development of an easily accessible and comprehensive compilation of reaction cross sections. 

Isenberg, G., Rathke, P.C., Hulsmann, N., Franke, W.W., Wolfarth-Botterman, K.E. (1976). Cytoplasmic actomyosin fibrils in tissue culture cells. Direct proof of contractility by visualization of ATP-induced contraction in fibrils isolated by laser microbeam dissection. Cell Tiss. Res. 166, 427-444. 

The United States leads in basic research related to implantation processes and in the development of equipment for conventional applications of ion implantation. Japan appears to have the initiative in the development of equipment for ion microbeam technologies. 

It is felt that the use of electron microbeam methods offers the basis for a revolutionary new approach to the study of catalyst particles. Some results can be obtained immediately but to realise the full potential of the method a considerable amount of further exploration of data collection and data analysis methods will be needed. 

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). 

The second source of partitioning data is experimental equilibration of crystals and liquids followed by microbeam analysis of quenched run products. Starting materials can be natural rocks, or synthetic analogues. In either case it is customary to dope the starting material with the U-series element(s) of interest, in order to enhance analytical precision. Of course, doping levels should not be so high as to trigger trace phase saturation (e g.. 

Table la. Sources of partitioning data Microbeam or track-counting analyses of coexisting crystals and matrix (or glass) in natural rocks. 

There are surprisingly few microbeam studies of zircon-melt partitioning in natural systems and none in experimental systems. Recently Thomas et al. (2002) have derived zircon-melt partition coefficients from rehomogenised glass inclusions in zircons from an intrusive tonalite, while Hinton et al. (R. Hinton, S. Marshall and R. Macdonald, written comm.) have used an ion-microprobe to measure zircon-melt partition coefficients from a Kenyan peralkaline rhyolite, with an estimated eruption temperature of 700°C (Scaillet and Macdonald 2001). We have used the lanthanide partition coefficients from these two studies to derive best-fit values for and for the large Vlll-co-ordinated site. In total there are 13 individual sets of partition coefficients. All of these yield broadly consistent values of, in the range 0.968-1.018 A, but very variable, in the range 373-1575 GPa. Because Lu is comparable in size to cannot be well... 

PIXE has also been used for pigment analysis in furniture and interior painting [301a], The growing use of piPIXE and associated beam techniques in art and archaeometry is noticeable [302,303], Even delicate materials such as paper and parchment are unaffected by microbeams. 

The applications of high-energy ion microbeams have been collected in a monograph [304],... 

The first nuclear microbeam with a spatial resolution of 1 pm was built by Watt et al. (1981), and the first sub-micron instrument was built by Grime et al. (1987). Khodja et al. (2001) have published a description of the nuclear microprobe at the Pierre Sue Laboratory in France, which is a national facility dedicated to microbeam analysis. Its unique facility is that it is capable of analysing radioactive samples by means of a dedicated beamline. Figure 4.1 shows a schematic diagram of the apparatus. 

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