Single particle and collective excitations in the one-dimensional charge density wave solid K0.3MoO3 probed in real time by femtosecond spectroscopy

Ultrafast transient reflectivity changes caused by collective and single pa rticle excitations in the quasi-one-dimensional charge-density wave (CDW) s emiconductor K0.3MoO3 are investigated with optical pump-probe spectroscopy . The temperature dependence of nonequilibrium single particle excitations across the CDW gap and their recombination dynamics are reported for the fi rst time. In addition, amplitude mode reflectivity oscillations are observe d in real time. A T-dependent overdamped response it; also observed which i s attributed to relaxation of the phason mode.