Photodesorption of O2 from Ag-2 : A time-resolved study of Ag2O-2

We present time-resolved photoelectron spectra of mass-selected Ag2O2 anions. The anions are photoexcited by photons with an energy of 3.1 eV, and photoelectron spectra of the excited species Ag2O-2* and the subsequently appearing fragments are recorded using a probe laser pulse with a photon energy of 1.5 eV. The excited state of Ag2O-2 has a short lifetime of 130 fs±70 fs only and decays by direct photodesorption of O2. The data demonstrate the ability of time-resolved photoelectron spectroscopy (TR-PES) to observe the breaking of chemical bonds if the decay process of the excited state is direct (non-thermal desorption). The data are compared to recent results of a NeNePo experiment on the same system