July 1, 1995
Fluorescence of single nanocrystals via two-photon excitation
Each nanocrystal emits pure visible light whose color is controlled by its size.
Figure 1
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.
Figure 2
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.
Reference:
- "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).