The dynamical structure factor of the frustrated spin 1/2 Heisenberg model for a series of frustration parameters at finite temperatures is presented. A sharp upper boundary of the spinon continuum is found. A simple method to extract the nearest neighbour coupling J from the spectral width is suggested. Signatures of frustration are discussed and a comparison with neutron inelastic scattering data is given.

Categories: cond-mat

Dynamical properties of the compounds CuGeO_3 and \alpha'--NaV_2O_5 at temperatures $T\neq 0$