AMO seminar Thursday 23rd October 15:15-16:00 1525-323 Title: Photophysics of small carbon cluster anions Speaker: Klavs Hansen, University of Gothenburg / IFA Abstract: Small carbon clusters and carbon-based molecules have gained increasing importance in the attempts to understand the molecular zoo in interstellar space and the dynamics of the molecular clouds located close to nascent stars. One of the questions that needs to be answered is how energy is dissipated after a photon has been absorbed by a molecule. A number of potential decay channels are available, such as direct ionization, fluorescence, delayed ionization, and infrared radiation from vibrational transitions. These questions have been studied with visible and near-infrared photoexcitation and decay of anionic carbon clusters C−N, N= 4−7 and C6H−at the Tokyo Metropolitan University electrostatic storage ring. The experiments allowed a determination of the dominant channels and their timescales, which were found to differ by orders of magnitude from one anion to the next. Thermally excited electronic states play a crucial role for these differences, even for ions as small as C−4. The hows and whys of this novel cooling mechanism will be presented. Coffee, tea and cake will be served at 15:05