The spectral properties of new fluorene-based photosensitizes for efficient singlet oxygen production are investigated at room temperature and 77 K. Two-photon absorption (2PA) cross-sections of the fluorene derivatives are measured by the open aperture Z-scan method. The quantum yields of singlet oxygen generation under one- and two-photon excitation (ΦΔ and 2PAΦΔ, respectively), are determined by the direct measurement of singlet oxygen luminescence at ≈1270 nm. The values of ΦΔ are independent of excitation wavelength, ranging from 0.6-0.9. The singlet oxygen quantum yields under two-photon excitation are 2PAΦΔ≈1/2ΦΔ, indicating that the two processes exhibit the same mechanism of singlet oxygen production, independent of the mechanism of photon absorption.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry
- Singlet oxygen
- Two-photon absorption