Three-photon-induced fluorescence of diphenylhexatriene in solvents and lipid bilayers 3

Henryk Malak, Ignacy Gryczynski, Jonathan D. Dattelbaum, Joseph R. Lakowicz

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4 Scopus citations


We observed the emission of 1,6-diphenyl-1,3,5-hexatriene (DPH) when excited with the fundamental output of a fs Ti:sapphire laser at 860 nm. The emission spectra of DPH were identical to that observed for one-photon excitation at 287 nm. The dependence of the DPH emission intensity on laser power was cubic, indicating three-photon excitation of DPH at 860 nm. At a shorter wavelength of 810 nm, the dependence on laser power was quadratic, indicating a two-photon process. At an intermediate wavelength of 830 nm the mode of excitation was a mixture of two- and three-photon excitation. At 830 nm the anisotropy is no longer a molecular parameter, and the mode of excitation and anisotropy of DPH depends on laser power. Frequency-domain anisotropy decays of DPH in triacetin revealed the same rotational correlation times for two- and three-photon excitation. However, the time 0 anisotropy of DPH was larger for three-photon excitation than for two-photon excitation. Steady-state anisotropy data for DPH-labeled membranes revealed the same transition temperature for one- and three-photon excitation. These anisotropy data indicate that membrane heating was not significant with three-photon excitation and that three-photon excitation may thus be of practical usefulness in fluorescence spectroscopy and microscopy of membranes.

Original languageEnglish
Pages (from-to)99-106
Number of pages8
JournalJournal of Fluorescence
Issue number2
StatePublished - 1 Jan 1997


  • Anisotropy decays
  • Diphenylhexatriene
  • Fluorescence intensity decays
  • Membranes
  • Multiphoton excitation
  • Three-photon excitation
  • Two-photon excitation


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