Figure 2.
Monomer transient absorption. (a) Selected sub-ps TA timeslices following excitation at 2.6 eV with 26 μJ/cm2. A three-state model is sufficient to describe these data. The initial 1Bu PIA can only be clearly observed within the pump pulse duration (black), and it decays to form the well-known 2Ag PIA in the visible region. The region below 1.1 eV is magnified 10× to show the weak 2Ag → 1Bu PIA. (b) The corresponding decay kinetics (lines) show direct, instrument-limited conversion from 1Bu to 2Ag and rapid decay to the ground state. These processes are completely independent of pump fluence over nearly 2 orders of magnitude (symbols, data normalized with respect to pump intensity) The data for 0.78 eV are magnified by a factor of 4 for clarity.