Molecular Binoculars: How to Spatially Resolve EnvironmentalFluctuations by Following Two or More Single-Molecule Spectral Trailsat a Time.

We propose a novel type of spectraldiffusion experiment that enablesone to decouple spatial characteristics of the environmental fluctuations,such as their concentration, from the interaction with the chromophore.Traditional hole broadening experiments do not allow for such decouplingin the common case when the chromophore–environment interactionis scale invariant. Here we propose to simultaneously follow the spectraltrails of a small number of nearby chromophorestwo or morewhichthereby sense a highly overlapping set of the fluctuations. To thisend, we estimate the combined probability distribution for the frequenciesof a set of chromophores contained within the samesample. The present setup introduces a new length scale, i.e., theinterchromophore distance, which breaks the aforementioned scale invarianceand enables one to determine independently the concentration of theenvironmental fluctuations and their coupling to the chromophores,by monitoring the time after which spectral diffusion of distinctchromophores becomes uncorrelated. We illustrate these results withstructural excitations in low temperature glasses. [ABSTRACT FROM AUTHOR]