Electronic energy transfer from the S2 state of rhodamine 6G

Israel Kaplan*, Joshua Jortner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


In this paper we present the results of an experimental study of intermolecular electronic energy transfer (EET) from the short-lived Second excited singlet state of rhodamine 6G (R6G) to the ground state of 2,5-bis [5′-tert-butyl-2-benzoxazolyl] thiophene (BBOT). The S2 state of the donor was excited by sequential, time-delayed, two-photon excitation (STDTPE) utilizing the second harmonic and the first harmonic of a mode-locked Nd3+: glass laser, while the EET process was interrogated by monitoring the enhancement of the S1 → S0 fluorescence of BBOT. The enhancement of the fluorescence intensity of BBOT was found to be linear in the energies of the two exciting pulses, and linear in the concentration of the energy acceptor (over the BBOT concentration range of (0.3-7) × 10-5 M), which is in accord with the predictions of the Forster-Dexter mechanism for resonant EET from an ultrashort-lived donor state at low acceptor concentrations. Quantitative measurements of the S2 → S0 fluorescence yield in R6G solution directly excited by STDTPE and of the S1 → S0 fluorescence of BBOT from R6G + BBOT solutions resulting from EET led to the values of YD(S2 → S0) = (2.1 ± 0.5) × 10-6 for the emission quantum yield of the S2 state of R6G and τrD(S2) ≈ 3 × 10-14 s for the lifetime of the metastable S2 state of this molecule.

Original languageEnglish
Pages (from-to)381-396
Number of pages16
JournalChemical Physics
Issue number3
StatePublished - 15 Aug 1978


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