The ion beam can also be channelled down crystal axes and planes. Many of these techniques can be combined with channelling to study the lattice location of species (CCM - Channelling Contrast Microscopy).

MeV protons are very penetrating while producing very little sample damage. These qualities permit the in situ, non-destructive analysis and imaging of buried structures such as solid and fluid inclusions in minerals.

Detection of nuclear reaction induced gamma-rays, and detailed characterization of reaction cross-sections, has enabled quantitative analysis methods to be developed. The lower Coulomb barrier of light elements makes PIGE particularly suitable for the analysis of light elements such as Li, Be, B, F, Na, and Al.

The Laboratoire Pierre Sue, Saclay, and the Bruyeres le Chatel nuclear microprobe facility, Paris, have developed nuclear reaction methods for the measurement of ^1,2H, ^6,7Li, ^10,11B, ¹²C, ¹⁴N, ¹⁶O, ¹⁹F, ²³Na, ^24,25Mg, ²⁷Al, ²⁸Si, ³²S and ³⁵Cl in minerals (Courel et al., 1991; see review by Ryan and Griffin, 1993, and references therein). The isotopes ⁷Li, ¹⁹F, ²³Na, ^24,25Mg, ²⁷Al, ²⁸Si and ³⁵Cl are determined using (p,p'gamma) reactions (PIGE) at proton energies from less than 2 MeV up to 3.5 MeV, suitable for simultaneous PIXE analysis of heavier elements. A similar approach is taken by the Queen's University group (MacArthur and Ma, 1991). H is determined by elastic recoil detection (ERDA). The remaining isotopes are determined using (d,a), (d,p), (p,a) and (p,a gamma) reactions. The corresponding elemental detection limits for all elements between H and F are 10-50 ppm. For the elements Na and heavier the detection limits grow from ~200 to ~2000 ppm.

The notation used for nuclear reactions, (x,yz), denotes the incident beam particle "x" and the reaction products "y" and "z", where "p" is a proton, "d" is a deuteron (²H), "a" is an alpha particle (⁴He) and "g" or "gamma" denotes a gamma-ray. "p'" denotes an inelastically scattered proton; it leaves the target nucleus in an excited state.

Further Reading:

• C.G. Ryan, "The Nuclear Microprobe as a probe of earth structure and geological processes", Nucl. Instr. Meth. B104 (1995) 377-394.
• M.B.H. Breese, D.N. Jamieson and P.J.C. King, "Materials Analysis using a Nuclear Microprobe", Wiley and Sons, New York, 1996.

• P. Courel, P. Trocellier, M. Mosbah, N. Toulhoat, J. Gosset, P. Massiot and D. Piccot, Nucl. Instr. Meth. B54 (1991) 429.
• J.D. MacArthur and X.-P. Ma, J. PIXE 1 (1991) 311.
• C.G. Ryan and W.L. Griffin, "The Nuclear Microprobe as a tool in geology and mineral exploration", Nucl. Instr. Meth. B77 (1993) 381-398.