Two-color two-photon excitation of fluorescence

Joseph R. Lakowicz, Ignacy Gryczynski, Henryk Malak, Zygmunt Gryczynski

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


We report the observation of two-photon excitation of an organic fluorophore with two different wavelengths, a phenomenon we refer to as two- color two-photon (2C2P) excitation. Ultraviolet emission of p-terphenyl at 340 nm was observed when the sample was illuminated with both 375 and 750 nm pulses from a picosecond dye laser. The emission of p-terphenyl was about 100-fold and more than 1000-fold less for illumination at only 375 or 750 nm, respectively. Observation of the 2C2P signal required temporal and spatial overlap of the 375 and 750 nm pulses. The amplitude of the signal depended on the polarization of each beam. 2C2P excitation can have applications in fluorescence microscopy and elsewhere when spatially localized excitation is desirable.

Original languageEnglish
Pages (from-to)632-635
Number of pages4
JournalPhotochemistry and Photobiology
Issue number4
StatePublished - Oct 1996


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