A chemical or physical attribute of a chemical substance, chemical element, or mixture is determined using an analytical methodology. Analysis can be done in a variety of ways, ranging from simple weighing to complex approaches involving highly specialized instrumentation. Characterization is important not only for the design and development of new catalysts, but also for the development and optimization of processes, including scale-up and troubleshooting. Basic analytical methods that are extensively employed in laboratories are referred to as conventional methods of analysis. In the field of catalysis, novel in situ analytical techniques like photoionization and photoelectron photoion coincidence spectroscopy are being employed to detect gas-phase reactive intermediates.