Pennsylvania State University - Altoona College 1 article published in JoVE Chemistry An Introduction to Processing, Fitting, and Interpreting Transient Absorption Data Robert Hamburger1, Christopher Rumble2, Elizabeth R. Young1 1Department of Chemistry, Lehigh University, 2Department of Chemistry, Pennsylvania State University - Altoona College This protocol is a beginner's entryway into processing, fitting, and interpreting transient absorption spectra. The focus of this protocol is the preparation of datasets, and fitting using both single wavelength kinetics and global lifetime analysis. Challenges associated with transient absorption data and its fitting are discussed.