Time of Flight SIMS (TOF-SIMS) analysis

Time of Flight SIMS (TOF-SIMS) In TOF-SIMS analysis the sample is probed with a pulsed primary beam intended to ensure the primary “ion dose” remains below the static SIMS limits (1e11–1e12 ions/cm2). The secondary ions and molecules are analysed by a Time of Flight spectrometer (a flight tube) by measuring their exact time of travel in the spectrometer. The duration of the time of their travel is calibrated against their mass, which then provides a mass spectrum. The advent of pulsed primary beams and more recently of polyatomic ion sources, minimise “damage “ and ensures that the integrity of the molecular structure of the organics remains intact. The technique also provides high mass resolution spectra and due to its unlimited mass range allows the detection of very large molecular fragments. The high mass resolution capability will provide unambiguous “mass assignment “and hence resolve organic and inorganic SIMS fragments of the same nominal mass. The technique is also capable of chemical imaging which show the distribution of various atoms and molecules on a surface. In certain operation modes, TOF-SIMS images may be retrospectively interrogated to reveal the corresponding SIMS spectra from individual pixels. TOF-SIMS is also capable of depth profiling by sequential sputtering and analysis of a surface with parallel detection of all the elements. More recently the advent of new polyatomic ion sources (e.g. C60) will allow “non-destructive” depth profiling of certain organic materials. The applications of TOF-SIMS are detection and imaging of sub monolayer organic and inorganic contaminants, depth profiling and analysis of materials used in biomedical technologies.

For more information on Time of Flight SIMS (TOF-SIMS) analysis talk to Aystorm Scientific Ltd