ToF-SIMS (Time-of-flight secondary ions mass spectrometer)

• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: Funded in 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 550487435

The instrument object of this proposal is a Time-of-flight secondary ions mass spectrometer (ToF-SIMS). This is a surface-sensitive analytical method that uses a focused beam of ions (for example Cesium, Gallium or Bismuth) to remove/eject molecules or molecular fragments from the surface of a sample in high vacuum. Such fragments are ideally removed layer by layer and, since they are positively or negatively charged, can be collected and identified by a spectrometer based on their mass-to-charge m/Z ratio. This is done by measuring the time of flight, i.e. the time it takes them to reach the detector. In its most basic operation, the instrument can be used as a surface spectrometer to determine the chemical composition of such surface. However, given the layer-by-layer nature of the process, the instrument can also offer depth profiling, allowing excellent depth resolution down to roughly 3-5 nm. Depending on the mode in which it is operated, the instrument can also provide lateral imaging (resolution on the order of 40-50 nm). Therefore, one may even obtain 3D reconstructions of samples composition (hence 4D information, since every pixel contains a mass spectrum). Other than the spatial resolution, there are other possibilities with ToF-SIMS: i) wide range of masses detectable in parallel. This implies that the method is applicable to a very broad range of materials, including metals, oxides and even polymers and soft matter. ii) Sensitivity: trace elements can be detected in the ppm range and with resolutions far higher than 10000. iii) a high vacuum environment coupled with heating/cooling stages and with several possibilities for inert transfer of samples to/from gloveboxes allows high experimental flexibility and to work with samples unstable in atmospheric conditions. iv) It can also be combined with sputtering or focused-ion beams to obtain cross sectional imaging. The above-described instrument is therefore a unique tool with high flexibility to investigate a wide range of materials, describe their surfaces ́ chemical properties and morphology, as well as to observe their evolution towards the bulk and finally reconstructing full chemical volumetric information. Here, we propose to apply ToF- SIMS to a wide variety of materials and technologically relevant devices. The main application is the investigation of battery materials, from electrodes to solid electrolytes and to the respective interfaces, spanning Li-ion as well as new generation Na-ion, solid-state and Li-S batteries. Further applications will include fuel cells, metals and alloys, clays and various layered compounds, oxides for photoelectrochemical applications, as well as biological samples.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: ToF-SIMS (Flugzeit-Sekundärionen-Massenspektrometer)
• Instrumentation Group: 1720 Spezielle Massenspektrometer (Flugzeit-, Cyclotronresonanz-, Ionensonden, SIMS, außer 306)
• Applicant Institution: Universität Bayreuth
• Leader: Professor Dr. Matteo Bianchini