Raman Scattering versus Infrared Conductivity: Evidence for   one-dimensional Conduction in La_{2-x}Sr_{x}CuO_{4}
  Raman and Infrared (IR) spectra of an underdoped La_{1.90}Sr_{0.10}CuO_{4} single crystal have been measured as a function of temperature. Both techniques provide unconventional low-energy spectra. The IR conductivity exhibits features peaked at finite frequencies which do not have a counterpart in the Raman response. Below approximately 100 K a transfer of both Raman and IR spectral weight towards lower energies is found and a new component in the Raman response builds up being characterized by a very long lifetime of electrons propagating along the Cu-O bonds. 
F. Venturini, Q.-M. Zhang, R. Hackl, A. Lucarelli, S. Lupi, M.   Ortolani, P. Calvani, N. Kikugawa, T. Fujita