Large classes of metal clusters are expected to have dipole-allowed electronic transitions in the near-infrared, but precise experimental characterization of such low-lying states is lacking. Here, the authors probe cationic cobalt clusters of 4 to 15 atoms using IR photofragmentation spectroscopy with krypton as a messenger atom to show that low-lying electronic excited states are responsible for the size-dependent radiative decay of these highly excited clusters.
- Kevin A. Kaw
- Rick J. Louwerse
- Piero Ferrari
