Methods
Here you find an overview of the ion-beam based methods available at the Tandem Laboratory in alphabetical order.
AMS – accelerator mass spectrometry
AMS stands for Accelerator Mass Spectrometry and can be employed for isotope-specific analysis of material. The sample material is ionised and accelerated with a particle accelerator prior to mass analysis reaching a sensitivity of up to 1:1016. While the method is mostly known as the base for radiocarbon dating, it can also be used for the spectrometry of other elements providing important data for climate research, geology, hydrology, medicine and more.
Available at: MICADAS
IBA – ion beam analysis
Channelling
In a crystalline material, the atoms are arranged in a long-range order. If the incident ion beam is parallel to a string or plane of atoms, it travels on an oscillating trajectory along the channel formed by several atomic strings or planes. This effect is called channelling. Channelling affects the probability with which an ion encounters an atomic nucleus inside a sample and has therefore a strong influence on several IBA techniques such as RBS and NRA. As an example, the channelling effect can be used to reduce the signal of a crystalline substrate during an RBS measurement to improve sensitivity for light-element detection.
EBS
Elastic Backscattering Spectrometry (EBS) uses the strong increase in the scattering cross section at specific resonance energies to detect light elements (such as carbon, nitrogen or oxygen). These resonances correspond to elastic nuclear reactions between light projectiles (usually protons or helium) with the element of interest. The resulting enhanced signal in the backscattering spectrum, compared to standard RBS, improves both the detection limit and accuracy for light elements, particularly in scenarios where the signal would otherwise be obscured by that of heavier matrix elements.
Available at: Tandem – Beamline 1, Beamline 2, Beamline 4, Beamline 6
ERDA
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 profiles on the nanometre scale, focusing on lighter elements.
Available at: Tandem – Beamline 2, Beamline 4, Beamline 6
LEIS
Low-Energy Ion Scattering (LEIS) operates on the same physical principle as RBS and MEIS but employs primary ions of even lower energy. These low-energy ions cannot penetrate deep into a material but are instead scattered from the first few atomic layers. LEIS therefore is a technique ideal for studying surface and near-surface effects with a very high depth-resolution.
Available at: ToF-LEIS system
MEIS
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 characterisation of sensible materials. Additionally, the method can be employed for obtaining depth resolved information on the crystal structure of materials.
Available at: Implanter – Beamline 2
Microbeam
To additionally analyse the lateral distribution of elements in a sample, the ion beam is focused down to a few micrometres and scanned over the sample surface. IBA methods (PIXE, RBS, ERDA and NRA) can be used in combination with the microbeam to obtain a three-dimensional map of the sample’s chemical composition.
Available at: Tandem – Beamline 2
NRA
Nuclear Reaction Analysis (NRA) makes use of the fact that certain ion species undergo nuclear reactions in collision with target nuclei at a specific resonance 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.
Available at: Implanter – Beamline 3, Tandem – Beamline 1, Beamline 2, Beamline 4, Beamline 6
PIXE
Particle Induced X-ray Emission (PIXE) employs the ability of energetic particles to excite the target's electronic system and thus induce the emission of characteristic X-rays from the sample material. This method for measuring a sample’s chemical composition is especially sensitive and non-destructive.
Available at: Implanter – Beamline 3, Tandem – Beamline 2, Beamline 4, Beamline 6
RBS
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 nanometre scale, is particularly useful for heavier elements, as its sensitivity drastically increases with atomic number.
Available at: Tandem – Beamline 1, Beamline 2, Beamline 4, Beamline 6
IBMM – ion beam modification of materials
Ion Beam Modification of Materials (IBMM) employs energetic ions for tailoring material properties e.g. through modifying conductivity, doping or amorphising material. By ion implantation, properties of materials can be changed after growth of complex multi-layered structures. The depth of the intended modification can be chosen by altering the energy of the primary beam.