  Time-resolved optical spectroscopy of collective and single-particle
excitations of 1T-TaS2 and 2H-TaSe2 reveals the presence of a large gap in the
excitation spectrum on the femtosecond timescale, associated with the formation
of various degrees of CDW order. In common with superconducting cuprates,
excitations with energies less than the full gap show much slower relaxation.
This separation of timescales cannot be explained in a quasi-2D Fermi-Liquid
picture with an anisotropic gap but rather suggests the formation of a
fluctuating spatially inhomogeneous state eventually forming a long-range
ordered state at low temperatures.
