Analytical methods at the Tandem Laboratory in a nutshell
AMS stands for Accelerator Mass Spectrometry and can be employed for isotope-specific analysis of sample material with a sensitivity of 1:1016. The method is mostly known as the base for the radiocarbon dating methodology, but can also be used for dating other materials, to study the climate, sea currents and many more.
Rutherford Backscattering Spectrometry (RBS) is applied for non-destructive depth profiling of thin film systems by scattering of light primary ions from the target material. The method, which has a depth resolution at the nanometer scale, is particularly useful for heavier elements, as its sensitivity drastically increases with atomic number.
Elastic Recoil Detection Analysis (ERDA) is closely related with RBS but employs heavy primary ions for creating recoiling target atoms from a sample of interest. The method can deliver depth profiels on the nanometer scale, focusing on lighter elements.
In Particle Induced X-ray Emission (PIXE) the ability of energetic particle beam to excite the target's electronic system and thus induced emission of characteristic X-rays from the sample material is employed. This method for measuring a samples composition is particularly sensitive and non-destructive.
In particular RBS and PIXE can be performed in combination with high lateral resolution by employing a microbeam with a fem µm diameter. The beam can be scanned over the sample in order to obtain a three-dimensional mapping of the composition.
Nuclear Reaction Analysis (NRA) makes use of the fact that certain ion species can, in collisison with target nuclei undergo nuclear reactions, provided they have suitable primary energy. From the characteristic decay products one can subsequently reconstruct the composition of a sample, often depth resolved. NRA has unique capabilities, for example when it comes to non-destructive depth profiling of hydrogen in materials.
Medium-Energy Ion Scattering (MEIS) is a high-end version of conventional RBS. With even lower beam doses and higher depth resolution MEIS is of high relevance for the development of ultra-thin film systems and for characterization of sensible materials. Additionally, the method can be employed for obtaining depth resolved information on the crystall structure of materials.
Ion beams can be also employed for tayloring material properties e.g. modifying conductivity, doping, amorphising material, etc. By ion implantation properties of materials can be changed after growth of complex multi-layered structures. The depth of the intended modifications can be chosen by altering the energy of the primary beam.