Fluorescence of single nanocrystals via two-photon excitation. Each nanocrystal emits pure visible light whose color is controlled by its size.
Two-Dimensional Image Produced by Two-Photon Fluorescence-Excitation Microscopy of Semiconductor Nanocrystals
This image shows a 10 x 10 micron scan of a dilute concentration of high quantum yield ZnS-passivated 29 Angstrom diameter CdSe nanocrystals in poly(dimethylsiloxane). The z-axis indicates detected visible-wavelength fluorescence. The widths of the peak s are lmited by the two-photon excitation volume of 0.75 cubic microns. This scan was taken at room temperature under excitation at 800nm.
Low Temperature Large Ensemble / Single Nanocrystal Emission Spectra
This figure shows the contrast in emission between the as-synthesized inhomogeneously broadened emission spectrum of 55 Angstrom diameter CdS nanocrystals and that of the homogeneous linewidth (15meV) obtained under microscopic two-photon excitation. The excitation wavelength is 800nm and T= 10K.
- "Photoluminescence of Single Semiconductor Nanocrystallites by Two-Photon Excitation Microscopy", Sean A. Blanton, Ahmad Dehestani, Peter C. Lin, Philippe Guyot-Sionnest, Chem. Phys. Letts. 229, 317 (1994).