Temperature Dependence of the Spectral Function through the Peierls Transition in Quasi-One-Dimensional Compounds

High-resolution photoemission measurements have been carried out on blue-bronze materials (K 0.3 MoO 3 and Rb 0.3 MoO 3 ). In these quasi-one-dimensional systems, a metal-insulator transition at 180 K is associated with a lattice distortion, the formation of a charge density wave and the opening of an energy gap. In contrast to naive expectations, a modification of the spectral function over an energy range one order of magnitude larger than the energy gap is observed through the transition. This behaviour suggests that unusual mechanisms associated with the 1D character strongly modify the photoemission spectra.