Selective optical probing of the charge-density-wave phases in NbSe3

We report a study of the ultrafast single particle dynamics in quasi-one-dimensional NbSe3 whisker crystals using a two-color pump-probe measurement. A selective enhancement of the relaxation dynamics connected with one of the two charge-density-wave (CDW) phases was realized by tuning the probe energy to around 1.5 eV, in which the temperature dependence across the corresponding phase transition shows a pronounced anomaly. A similar selective excitation was possible in the coherent CDW oscillation.