Date: 2009. 5. 14, 5:00 PM Place: Mogam Hall, Bldg 500 - Abstract - Photodissociation of molecular ions such as C6H5NH2+, C6H5F+, C6H5Cl+, and C6H5Br+ has been examined using a tandem mass spectrometer consisting of two stages: an ionization and a photodissociation stage. In particular, MATI has been adopted to produce parent ions with precisely defined energies. They were energized by absorption of photons with various energies in the second stage, which eventually broke to give birth to daughter ions. The relevant decay constants of the parent ions with different internal energies have been estimated by analyzing the tails of the photodissociation mass peaks corresponding to the daughter ions and compared with the results based on the quasi-equilibrium theory (QET). Besides, we investigated the photofragmentation dynamics of cluster ions with hydrogen-bonding networks such as aniline+-(water)n and adenine2+-(water)n cluster ions. The average number of ejected water molecules measured as a function of photon energy revealed that the loss of water molecules is in essence a photoevaporation process.