Nss software

A Hitachi HD-2300A equipped with Thermo Scientific NORAN System 7 EDS detectors was operated at 200 kV for STEM imaging in ADF, HAADF, BF, and SE modes as well as for EDS analysis. A JEOL JEM-3200FS was operated at 300 kV for HRTEM. In both microscopes, Gatan 626 single tilt liquid nitrogen cryo transfer holders were used to support the samples. The samples were inserted into the microscope column and then cooled down to cryogenic conditions under vacuum by liquid nitrogen before electron irradiation. In situ (HA)ADF movies were recorded at a resolution of 512 px × 512 px, a scan area of 51.79 nm × 51.79 nm, and pixel dwell times of 20 μs (Movie S1) or 7.5 μs (Movie S2). The probe current was 0.168 nA. EDS analysis was performed after fixing the area of interest by scanning the area using a lower flux electron beam until the nanoparticles did not grow further. EDS of individual nanoparticles was performed with manual drift correction based on the HAADF signal. EDS quantification was performed with the Thermo Scientific NSS software after background removal and matrix correction by the Proza method (Phi-Rho-Z). A Gatan K2 Summit direct electron detector was used for HRTEM imaging at a resolution of 3710 px × 3838 px (pixel size is 0.013 nm for the imaging conditions used).