Detection and characterization of single molecules in aqueous solution

摘要: Using a confocal microscope with single-photon avalanche photodiode as detector, we studied photon bursts of single Rhodamine 6G (R6G) and Rhodamin B-zwitterion (RB) molecules in aqueous solution by excitation the lowest excited singlet stateS 1 frequency-doubled titanium: sapphire laser. Multichannel scaler traces, fluorescence autocorrelation function decay times determined time-correlated counting have been measured simultaneously. The time-resolved signals were analyzed maximum likelihood estimator. Fluorescence lifetime patterns steps 100 ps generated convolution pulse. theS 1 state was derived from Kullback-Leibler minimum discrimination information. We are able to demonstrate for first time identification two different dye via their characteristic lifetimes 1.79 ± 0.33 ns 3.79 0.38 solution.