Tutorial: Transient Absorption Spectroscopy for Probing Ultrafast Dynamics

Transient absorption spectroscopy (TAS) is an indispensable technique for directly tracking chemical and physical dynamics on ultrafast time scales. This Tutorial covers the basic principles behind TAS and illustrates with examples its application in probing and understanding ultrafast photophysical and photochemical processes in chemistry, physics, biochemistry, and materials science. We also discuss how TAS data are analyzed mathematically and kinetically to gain physical and mechanistic insights into complex dynamic processes. By providing practical guidance from experimental design to quantitative kinetic modeling, this Tutorial aims to equip researchers with the foundational knowledge to effectively utilize TAS for ultrafast studies of different processes in molecules and materials.