Thermal history and temperature-dependent photon echo and hole burning linewidths in low temperature glycerol glasses

Temperature-dependent two-pulse photon echo and hole burning linewidths are reported for the system resorufin in glycerol glass from 1 to 25 K. At low temperature a factor of ~4 difference between the linewidths measured by the two techniques is observed owing to the broad fluctuation rate distribution of glass dynamics. Using cooling rates of 600 K/min and 0.2 K/min, it is shown that the linewidth of both spectroscopies is markedly dependent on how the sample was prepared. In terms of the two level system model of glass dynamics, the cooling rate dependence has direct implications on the structure of the glass at low temperature.