Ultrafast photoelectron spectroscopy: Femtosecond pump-probe coincidence detection of ammonia cluster ions and electrons

A new type of experiment is described, in which the femtosecond pump-probe method is combined with the photoelectron-photoion coincidence technique and time-of-flight photoelectron energy analysis. The experimental conditions for observing true coincidences are discussed. The performance of the new time resolved, ultrafast photoelectron spectroscopy is exemplified by studying the excited state dynamics of ammonia molecules and clusters