Increased source brightness could also be leveraged to increase the depth resolution of NanoSIMS analyses while maintaining high lateral resolution. Depth profiling-the practice of using the primary ion beam to erode through the sample while collecting compositional data-is a standard SIMS method that can achieve a few nanometer depth resolution . By comparison, the depth resolution of the NanoSIMS series of instruments is on the order of 10s of nanometers because the normal incident 16 keV primary ion beam penetrates into the sample to depths >20 nm . Depth resolution could be improved by lowering the primary ion beam impact energy, but at the cost of lower lateral resolution. Higher source brightness would regain some of the loss in lateral resolution, which would allow depth profiling of features that cannot be resolved with standard SIMS instruments, such as thin film transistors and attached bacteria.