Manifestation of tunneling TLS dynamics of a polymer matrix in single-molecule fluorescence blinking
Blinking (stochastic intermittence) of fluorescence is a quite common phenomenon that accompanies the emission of single quantum objects-organic chromophore molecules, quantum dots, and nanocrystals. It is demonstrated that fluorescence blinking of single organic molecules embedded into a polymer matrix including the occurrence of “grey” states is due to tunneling transitions in the two-level systems (TLSs) of the matrix. The repeated registration of fluorescence excitation spectra of single molecules (SMs) is used for our analysis. The statistics of fluorescence blinking of an SM is directly related to conformational changes (tunneling transitions in TLSs) in its immediate vicinity. Individual parameters of the corresponding elementary excitation are also determined.