Plasmon dispersion in quasi-one-dimensional (TaSe4)(2)I and K0.3MoO3

We present results of experiment al and theoretical studies of the plasmon dispersion in the quasi-one-dimension al conductors (TaSe4)(2)I and K0.3MoO 3 For both compounds, the dispersion relation, as measured by electron ener gy-loss spectroscopy in transmission, is quasilinear over a wide momentum r ange. Different theoretical approaches are discussed to explain the data, a ll based on a one-band model within the framework of the random-phase appro ximation. From this analysis, we find in contrast to photoemission measurem ents no hint for singular one-dimensional properties.