  Time-and-frequency resolved pump-probe optical spectroscopy is used to
investigate the effect of the impulsive injection of delocalized excitations
through a charge-transfer process in insulating CuGeO3. A large broadening of
the charge-transfer edge is observed on the sub-ps timescale. The modification
of this spectral feature can not be attributed to the local increase of the
effective temperature, as a consequence of the energy absorbed by the pump
pulse. The measured modifications of the optical properties of the system are
consistent with the creation of a non-thermal state, metastable on the ps
timescale, after the pump-induced impulsive modification of the electron
interactions.
