Phototransformation in visible and near‐IR femtosecond pump‐probe studies of C60 films

The ultrafast non‐linear optical dynamics of C60 thin films were investigated at low excitation levels. The pump‐probe response observed at low power is found to differ significantly from the ultrafast non‐exponential behavior observed at higher intensity. It is determined that the ultrafast relaxation processes measured at higher fluence levels are affected by phototransformation of C60.