Linewidth study of the dye molecule quinizarin in solid alcohol glasses

A detailed study of the hole-burning linewidth of the dye molecule quinizarin in amorphous alcohol glasses is presented. The experiments cover a temperature range between 400 mK and 4 K; the linewidth follows a Tα law with α between 1 and 1.3. An extrapolation of the low-temperature data, assuming α=1, yields a residual linewidth which is, within our experimental accuracy, lifetime limited.