Determination of distance distribution functions by singlet-singlet energy transfer.

The efficiency of energy transfer between two chromophores can be used to define an apparent donor-acceptor distance, which in flexible systems will depend on the R(0) of the chromophores. If efficiency is measured as a function of R(0), it will be possible to determine the actual distribution function of donor-acceptor distances. Numerical procedures are described for extracting this information from experimental data. They should be most useful for distribution functions with mean values from 20-30 A (2-3 nm). This technique should provide considerably more detailed information on end-to-end distributions of oligomers than has hitherto been available. It should also be useful for describing, in detail, conformational flexibility in other large molecules.