Navigating Government Guidances for Developing Combination Products

摘要

The increased availability in recent years of cluster ion beam such as C60 has opened up new areas of applications for time-of-flight secondary ion mass spectrometry (ToF-SIMS). In particular, it is now possible to acquire 3D images and molecular depth profiles of organic polymers and biological tissue sections. Ion cluster sources such as C60, Am and SF5 are used to sputter through these samples with high secondary ion yields and without causing significant residual damage below the sputter crater. Then either a cluster or monoatomic ion source is used to periodically analyze the sample between sputter cycles. Numerous research studies are examining the sputter process and investigating how to optimize the quality of the 3D images and molecular depth profiles. A common approach is to use the dual-beam mode, where a high-energy analysis beam (e.g., Bin+ at 25 keV) is used in tandem with a sputter beam of similar energy (e.g., C60+ at 20 keV) to create 3D images with excellent lateral and depth resolutions. We have shown that the ratio of the analysis beam dose density to that of the sputter beam should be kept below 2% to minimize damage in organic systems.