Single-molecule detection by two-photon excitation of fluorescence

Christoph Zander; Leif Brand; C. Eggeling; Karl-Heinz Drexhage; Claus A. M. Seidel

doi:10.1117/12.273568

7 May 1997 Single-molecule detection by two-photon excitation of fluorescence

Christoph Zander, Leif Brand, C. Eggeling, Karl-Heinz Drexhage, Claus A. M. Seidel

Proceedings Volume 2980, Advances in Fluorescence Sensing Technology III; (1997) https://doi.org/10.1117/12.273568
Event: BiOS '97, Part of Photonics West, 1997, San Jose, CA, United States

Abstract

Using a mode-locked titanium: sapphire laser at 700 nm for two-photon excitation we studied fluorescence bursts from individual coumarin 120 molecules in water and triacetin. Fluorescence lifetimes and multichannel scaler traces have been measured simultaneously. Due to the fact that scattered excitation light as well as Raman scattered photons can be suppressed by a short-pass filter a very low background level was achieved. To identify the fluorophore by its characteristic fluorescence lifetime the time-resolved fluorescence signals were analyzed by a maximum likelihood estimator. The obtained average fluorescence lifetimes (tau) _av equals 4.8 +/- 1.2 ns for coumarin 120 in water and (tau) _av equals 3.3 +/- 0.6 for coumarin 120 in triacetin are in good agreement with results obtained from separate measurements at higher concentrations.

Citation Download Citation

Christoph Zander, Leif Brand, C. Eggeling, Karl-Heinz Drexhage, and Claus A. M. Seidel "Single-molecule detection by two-photon excitation of fluorescence", Proc. SPIE 2980, Advances in Fluorescence Sensing Technology III, (7 May 1997); https://doi.org/10.1117/12.273568

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