A PiFM spectral library for the identification of molecular contaminants in geochemical laboratories
Description
Photo-induced Force Microscopy (PiFM) is a nanoanalytical technique that merges the simultaneous acquisition of Atomic Force Microscopy (AFM) topographic data with infrared (IR) phase identification. By using the attractive forces between a sample surface and a sharp, metal-coated cantilever tip mounted on an AFM, PiFM achieves a spatial resolution of approximately 5 nm when illuminated with a tunable IR laser (Nowak et al., 2016; Otter et al., 2021). Due to its high sensitivity that allows for the detection of molecular monolayers, PiFM is particularly effective for identifying and visualizing phases on the nanoscale, making it an excellent complement to other nanoscale imaging and elemental analysis techniques such as Scanning/Transmission Electron Microscopy (S/TEM) and Atom Probe Tomography (e.g., Otter et al., 2023). Sample preparation for PiFM poses significant challenges that must be overcome for artifact-free imaging andaccurate interpretation. This is critical as the materials used for mounting, polishing, and storing can leave molecular traces on the sample surfaces, which can complicate data interpretation. Hence, this spectral library presents PiFM spectra of traditional sample preparation and storage materials that will help identify and avoid potential contamination sources during analyses. The spectral library tab (Sup Table 1) includes the averages and first standard deviations (± 1s) of all measurments, normalized to the highest intensity for all measured sample preparation and storage materials for the three laser wavenumber ranges 755-1875 cm-1 (Block Engineering quantum cascade laser), 2000-2400 cm-1 (DRS Daylight Solutions MIRcat quantum cascade laser), and 2400-4400 cm-1 (EKSPLA PT200 optical parametric oscillator). The tab following the spectral library lists the analysed products (Sup Table 2). References: Förster, M. W., Chen, C., Foley, S. F., Alard, O., Yaxley, G. M. (2024). Fluid loss to the fore-arc controls the recycling efficiency of nitrogen in subduction zones. Chemical Geology, 121985. Nowak D., Morrison W., Wickramasinghe H.K., Jahng J., Potma E., Wan L., Ruiz R., Albrecht T.R., Schmidt K., Frommer J., Sanders D.P. and Park S. (2016) Nanoscale chemical imaging by photoinduced force microscopy. Science Advances, 2, e1501571. Otter, L.M., Förster, M.W., Belousova, E., O’Reilly, P., Nowak, D., Park, S., Clark, S., Foley, S.F., Jacob, D.E. (2021) GGR Cutting-Edge Review: Nanoscale Chemical Imaging by Photo-Induced Force Microscopy: Technical Aspects and Application to the Geosciences. Geostandards and Geoanalytical Research, 45(1), 5-27. Otter, L. M., Eder, K., Kilburn, M. R., Yang, L., O’Reilly, P., Nowak, D. B., Cairney, J. M., Jacob, D. E. (2023). Growth dynamics and amorphous-to-crystalline phase transformation in natural nacre. Nature Communications, 14(1), 2254.