Anomaly of the Nonergodicity Parameter and Crossover to White Noise in the Fast Relaxation Spectrum of a Simple Glass Former

Abstract

We present quasielastic light scattering and dielectric spectra of the glass former alpha-picoline. At high temperatures the evolution of the susceptibility minimum is well described by the mode coupling theory (MCT). Below the critical temperature T(c) the simple scaling laws of MCT fail due to the appearance of the excess wing of the alpha process, which shows a universal evolution as a function of log(10)tau(alpha). Taking this into account, however, we observe the predicted cusplike anomaly of the nonergodicity parameter as well as a crossover to "white noise."