Measuring the two-photon absorption cross sections of thiol-capped CdTe quantum dots in living cells

A modality to measure the two-photon absorption cross sections (TPACSs) of thiol-capped CdTe quantum dots (QDs) in living cells was established. The photoluminescence (PL) quantum yield ( Φ ) of cellular QDs was measured by the established relationship of Φ versus PL lifetime of cellular QDs. Then the local concentration of cellular QDs with the determined Φ in the measured region was obtained by the calibration curve of the PL intensity versus the QD aqueous concentration. The TPACSs of cellular QDs were gotten finally according to the measured PL intensity with the method of two-photon induced PL.