Accelerator Mass Spectrometry Techniques and Applications

Accelerator Mass Spectrometry (AMS) is a highly sensitive analytical method that counts individual rare isotopes within a sample by accelerating ions to high energies and separating them from abundant isobaric interferences. Originally developed for radiocarbon dating, AMS has been extended to a broad spectrum of applications including cosmogenic nuclide dating in geology and palaeoclimatology, tracing of environmental radionuclides, biomedical assays of long-lived radioisotopes and nuclear safeguards. Modern AMS systems integrate optimised ion sources, high-energy tandem accelerators or single-stage spectrometers and novel isobar suppression techniques to achieve detection limits down to a few atoms per sample. Recent technical advances encompass refined sample matrices such as metal oxides or fluorides to enhance negative ion yields, laser-based photodetachment methods for near-complete removal of atomic and molecular isobars, and highly efficient radiofrequency quadrupole (RFQ) ion coolers for improved beam transport and purity. Together, these developments have expanded the range of analysable nuclides, reduced measurement uncertainties, shortened analysis times and opened new avenues in earth science, archaeology, environmental monitoring and nuclear forensics.

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Innovations in isobar suppression through Ion-Laser InterAction Mass Spectrometry (ILIAMS) have delivered unprecedented background reduction for several key isotopes. By overlapping a tunable laser beam with cooled anion streams in an RFQ, ions with lower electron affinity are selectively neutralised, yielding suppression factors of up to 10¹⁰. This approach has enabled routine high-precision measurements of 36Cl, 26Al and emerging nuclides such as 135Cs without extensive chemical pre-separation and is compatible with AMS machines of varying terminal voltages.

A comprehensive methodological study has addressed the challenge of measuring cosmogenic 10Be and 26Al at very low nuclide concentrations. By operating in the 3+ charge state with optimised stripper gas compositions at 4–6 MV, laboratories have attained ion transmission efficiencies above 35–40 % and achieved 5 % precision on isotope ratios down to 10⁻¹⁴. Detailed sensitivity analyses of background events and data-reduction algorithms now inform blank correction protocols, ensuring reliable quantification for samples with only a few thousand atoms per gram.

Focus on sample preparation has highlighted the critical role of oxide matrix optimisation for beryllium measurements. Systematic tests of BeO formation parameters, including choice of binding agents and conductor materials, demonstrated that replacing niobium with silver as a matrix conductor can improve ion source currents and beam stability. Such refinements in cathode composition and pressing techniques are instrumental in boosting overall measurement throughput and lowering procedural blanks for routine 10Be analyses.

Accelerator Mass Spectrometry Techniques and Applications publication trend

The graph below shows the total number of articles in accelerator mass spectrometry techniques and applications across all publications each year (not limited to Nature Index journals).

Technical terms

Accelerator Mass Spectrometry (AMS): A technique that accelerates ions to high energies to separate and count rare isotopes against abundant molecular and atomic interferences.

Isobar: A nuclide that shares the same mass number but differs in atomic number, requiring specialised suppression methods in AMS.

Ion-Laser InterAction Mass Spectrometry (ILIAMS): A method that employs laser photodetachment in a cooled ion beam to selectively neutralise specific isobaric contaminants.

Cosmogenic nuclide: A rare isotope produced by interactions between cosmic rays and nuclei in the Earth’s atmosphere or surface materials, used for dating and tracing processes.

Radiofrequency Quadrupole (RFQ) ion cooler: An ion optical device that reduces beam energy spread and emittance via collisional cooling, enhancing transmission and purity in AMS.

References

1. 5 YEARS OF ION-LASER INTERACTION MASS SPECTROMETRY—STATUS AND PROSPECTS OF ISOBAR SUPPRESSION IN AMS BY LASERS. Radiocarbon (2021).
2. Highly sensitive 26Al measurements by Ion-Laser-InterAction Mass Spectrometry. International Journal of Mass Spectrometry (2021).
3. Technical note: Accelerator mass spectrometry of 10Be and 26Al at low nuclide concentrations. Geochronology (2022).
4. Influence of cathode materials on BeO currents in cosmogenic 10Be measurements using a SNICS ion source and accelerator mass spectrometry. Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms (2025).
5. Fluoride sample matrices and reaction cells — new capabilities for isotope measurements in accelerator mass spectrometry. EPJ Web of Conferences (2012).
6. Optimization of BeO formation parameters for the measurement of 10Be by AMS.. Journal of Physics Conference Series (2023).