High-throughput synthesis techniques can substantially cut down the time required to prepare large numbers of catalyst candidates. Figuring out which candidates work best, however, can be tricky. Cornell University chemists Xiaochun Zhou, Peng Chen, and coworkers report in ACS Catalysis a scalable imaging technique that can monitor and evaluate large numbers of individual catalyst particles in real time (2013, DOI: 10.1021/cs400277a). The method, which is based on fluorescence microscopy, reveals which nanosized particles among thousands are most active at catalytically converting nonfluorescing reactants—in a pair of correlated reactions—to fluorescing products. The team demonstrated that the technique offers a best-case spatial resolution of roughly 15 nm (30- to 40-nm resolution is typical) and is not limited to pinpointing promising catalysts for reactions that yield fluorescent products. The researchers note that the method provides greater data throughput and spatial resolution than other techniques that detect single particles. They add that it can be coupled with high-throughput catalyst preparation methods to accelerate development of new and better catalysts.