The techniques of ion beam analysis are used to determine the constituents of a sample. Thus, the object to be analyzed is used as a target for a beam of accelerated particles. The interactions of the beam particles with the nuclei or atoms of the target material can induce the emission of X rays (in the case of atoms) or gamma rays (for nuclei), which have a characteristic energy of the atom or emitter core. The beam particles with the target material can also be scattered, and the scattering angle and energy is also dependent upon the elemental composition of the material used as target. The analysis with ion beams can also be performed in air, by extracting the beam of particles to the atmosphere after passing through a thin window separating the vacuum environment, needed for producing the particle beam, from the external environment. Therefore, the object to be analyzed can be kept in their "natural" environment, thus avoiding the need to remove samples.

 

The production of the beam of particles is performed at the Laboratory of Materials and Ionic Beams, University of São Paulo, and the available techniques used for the analysis of historical and artistic materials are:

 

 

Rutherford Scattering in angular momentum (RBS)

Particle-induced X-ray emission (PIXE)

Particle-induced γ-ray emission (PIGE)

 

 

 

 

 

Advantages:

 

They are not destructive to most materials with the exception (if not taking precautions) of sensitive to heat or ionizing radiation organic compounds.

Allows the identification of several elements, including light elements such as Li, B, F, Na, Mg, and even hydrogen.

Quantitative analysis with an accuracy better than 5%;

The analysis techniques RBS, PIGE and PIXE are complementary and can be performed simultaneously.

Can be used for measurements in air (extracted beam) and thus directly on the objects in the museum, not requiring samples.

Limitations:

 

The analysis is strictly elementary, and there is any information about the chemical state of elements.

It is limited to measures only on the surface of the material (10 to 20 microns or less) and, therefore, may not be representative of the internal composition in the case of alteration on the surface.

 

 

 

 

 

Bird J.R., R.A Brown, D.D. Cohen and J.S. Williams, " Ion Beams for Material Analysis ", eds J.R. Bird and J.S. Williams, Academic Press, Sidney, 1989.

Tesmer J.R., M. Nastasi, " Handbook of modern ion beam analysis ", Material Research Society, Pittsburg, 1995.

Chu W.-K., J.W. Mayer, M.A. Nicolet, " Backscattering Spectrometry ", Academic Press, Boston, 1978.

S. A. E. Johansson, J. L. Campbell, "PIXE, A Novel Technique for Elemental Analysis", John Wiley and Sons, 1988.

Johansson S.A.E, J.L. Campbell, K.G. Malmqvist, " Particle induced X-ray Emission Spectrometry (PIXE) ", John Wiley and Sons, New York, 1995.

Dran J.-C., Calligaro T., Salomon J., "Particle induced X-ray Emission" in Modern Analytical Methods in Art and Achaeology, eds Ciliberto and Spoto, Vol 155 in Chemical analysis, John Wiley, New York, 2000.