Nuclear microprobe analysis

Some relevant terms for activation analysis are activation analysis, neutron activation analysis (NAA), instrumental neutron activation analysis (INAA), neutron activation analysis with radiochemical separation (RNAA), photon activation, neutron capture prompt gamma activation analysis (PGAA), charged particle activation, autoradiography, liquid scintillation counting, nuclear microprobe analysis, radiocarbon (and other element) dating, radioimmunoassay, nuclear track technique, other nuclear and radiochemical methods. Briefly, the salient features of some of the more popular techniques are as follows ... 

Neutron Activation Analysis X-Ray Fluorescence Particle-Induced X-Ray Emission Particle-Induced Nuclear Reaction Analysis Rutherford Backscattering Spectrometry Spark Source Mass Spectrometry Glow Discharge Mass Spectrometry Electron Microprobe Analysis Laser Microprobe Analysis Secondary Ion Mass Analysis Micro-PIXE... 

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. 

Breese, M.B.H., Jamieson, D.N. King, P.J.C. (1996) Materials Analysis Using a Nuclear Microprobe, John Wiley Sons, Inc, New York. 

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. 

Reiche, I., Yignaud, C., Favre-Quattropani, L., and Menu, M. (2002b). Fluorine analysis in biogenic and geological apatite by analytical transmission electron microscopy and nuclear reaction analysis. Journal of Trace and Microprobe Techniques 20 211-231. 

See the proceedings of the following International Conferences appeared in special issues of Nuclear Instruments and Methods in Physics Research Section B Nucl. Instrum. Methods Phys. Res. B 2002, 193, Proc. of the 19th Intern. Conf. on Atomic Collisions in Solids Nucl. Instrum. Methods Phys. Res. B 2002,190, Proc. of the I5th Intern. Conf. on Ion Beam Analysis Nucl. Instrum. Methods Phys. Res. B 2001, 175-177, Proc. of the 12th Intern. Conf. on Ion Beam Modification of Materials Nucl. Instrum. Methods Phys. Res. B 2001,18I, Proc. of the 7th Intern. Conf. on Nuclear Microprobe Technology and Applications. 

Kristiansson, P. et al., Photon-tagged nuclear reaction analysis — evaluation of the technique for a nuclear microprobe, Nucl. Instr. Meth. B, 136-138, 362, 1998. 

Megaelectron volt (MeV) ion beam techniques offer a number of non-destructive analysis methods that allow to measure depth profiles of elemental concentrations in material surfaces. Elements are identified by elastic scattering, by specific nuclear reaction products or by emission of characteristic X-rays. With nuclear microprobes raster images of the material composition at the surface can be obtained. Particle-induced gamma-ray emission (PIGE) is especially suited for fluorine detection down to the ppm concentration level. 

In the following, those ion beam analysis techniques that allow for fluorine detection will be presented. By far, the most important technique in this respect is nuclear reaction analysis (NRA). Although it can be rather complex to perform, it is the most often applied technique for fluorine trace element studies, due to a number of convenient and prolific resonant nuclear reactions which make it very sensitive to fluorine in most host matrices. NRA is often combined with particle-induced X-ray emission (PIXE) which allows for simultaneous determination of the sample bulk composition and concentrations of heavier trace elements. By focusing and deflecting the ion beam in a microprobe, the mentioned techniques can be used for two- or even three-dimensional multi-elemental imaging. 

G. Demortier, Analysis of light elements with a nuclear microprobe - a review, Nucl. Instr. Meth. B104 (1995) 244-254. 

Breese M B H, Jamieson D N and King P J C 1996 Materials Analysis with a Nuclear Microprobe (New York ... 

Figure 5 A multidetector setup used in combination with a nuclear microprobe. Types of spectra obtained are indicated. PIGE, particle-induced y-ray emission and PBA, prompt radiation analysis. See text for further explanation.

Particle-induced X-ray emission (PIXE) is an elemental analysis technique that employs a beam of energetic heavy charged particles (usually protons of 1-4 MeV) to induce element-specific X-ray emission. Depending on the sample material and thickness and on the conditions of the analysis, the technique offers detection limits at the 0.1-10 mg kg concentration level for low-Z matrices. Applied in nuclear microprobes, micro-PIXE combines a high sensitivity with the possibility of providing elemental maps with a lateral resolution in the sub-micrometer range. 

Figure 5 Components (not to scale) of a typical nuclear microprobe system (A) electrostatic particle accelerator (B) primary object aperture (C) secondary collimator (D) focusing system (E) scanning system (F) video camera and microscope (G) surface barrier detector for scattered particles (H) X-ray detector (I) specimen (J) surface barrier detector for transmitted particles (STIM) (K) front-end CAMAC with data bus (L) main computer and display with elemental map. (Reprinted with permission from Maenhaut W and Malmqvist KG (2001) Particle-induced X-ray emission analysis. In Van Grieken RE and Markowicz AA (eds.) Handbook of X-Ray Spectrometry, 2nd edn. Ch. 12, pp. 719-809. New York Dekker Marcel Dekker Inc.)...

Although the techniques of ion beam analysis (IBA) have been used for many years with broad beams (5-10 mm diameter), it is only in the 1990s that the technology for focusing high-energy ion beams has developed to the point where the spatial resolution is comparable to that of other forms of probe beam microanalysis (around 1 pm). The interactions most commonly used require protons with energy of 1-4 MeV for optimum sensitivity, and in this form the instrument is commonly known as the proton or nuclear microprobe. 

Using a combination of analytical techniques, the nuclear microprobe can provide simultaneous multi-elemental analysis over the entire Periodic Table with a spatial resolution of 1 pm, a minimum detection limit of 1-100 ppm depending on the conditions and a quantitative accuracy of 5-20% depending on the type of analysis. Although the penetration depth of MeV protons can be in the region of 100 pm in some materials, the nuclear microprobe is a surface-biased technique since signals are detected preferentially from the near surface region ( 10 pm depth). 

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