We examined the emission spectra, intensity decays, and anisotropy decays of the DNA-4′,6-diamidino-2-phenylindole (DAPI) complex resulting from one- and two-photon excitation of fluorescence. Similar lifetimes and correlation times were recovered from the frequency-domain data. However, the initial anisotropies of DAPI for one- and two-photon excitation revealed different angles between the absorption and the emission oscillators, 17.8 and 23.8°, respectively. This suggests the presence of two overlapping transitions in DAPI with different one- and two-photon cross sections for absorption.
- 4′,6-Diamidino-2-phenylindole-DNA complex
- anisotropy decay
- fluorescence intensity
- one- and two-photon excitation