Transient absorption spectroscopy is an effective method for characterizing excited states of molecules. Also called laser flash photolysis or pump-probe experiments, transient absorption relies on quickly populating the excited state followed by probing the excited state. In order to obtain an “instantaneous” population of excited states within a sample, a laser source is generally used. Detection of the excited state is commonly performed by a xenon lamp. Measurements are recorded by a PMT or CCD camera detector connected to a personal computer. Additionally, time-resolved measurements are possible, allowing for kinetic data of the excited states to be obtained.