An investigation of the effects of two level system coupling on single molecule lineshapes in low temperature glasses

A theoretical framework for determining the lineshapes of single molecules in low temperature glasses is presented. Our methods, in contrast to previous efforts, include coupling between two level systems (TLSs). This framework is applied to the physical system consisting of the chromophore terrylene embedded in the amorphous host polystyrene. We analyze the effect of TLS-TLS coupling on both individual lineshapes and linewidth histograms. Ourresults indicate that, although TLS-TLS coupling is certainly capable of producing noticeable changes in individual spectral lines relative to the uncoupled results, linewidth histograms are relatively unaffected by said coupling. An interpretation of this result is suggested. (C) 1998 American Institute of physics.