Figure 2.

Optical characterizations of QD-AB conjugates. (A) Absorption (dotted lines) and PL (solid lines) of QD605 (blue), QD655 (green) and QD705 (red). To show the spectral overlap between Tb emission and QD absorption and the differences in PL wavelengths also the Tb PL spectrum is shown (gray spectrum in the background). Förster distances were calculated as R₀(QD605) = 8.8 ± 0.4 nm, R₀(QD655) = 10.5 ± 0.5 nm, and R₀(QD705) = 11.2 ± 0.6 nm; (B) Pulsed (405 nm diode laser at 1 MHz) excitation was used to measure the PL decay curves at the respective PL peaks of the QDs. The multi-exponential decay curves (same colors as in A) gave amplitude-averaged decay times of τ(QD605) = 6.3 ± 1.2 ns, τ(QD655) = 14.0 ± 0.9 ns, and τ(QD705) = 80.0 ± 3.0 ns.