nanoparticles and, in addition, a broad shoulder on the side of the longer wavelength
that is clearly associated with the emission of the Ir(III) complex. Additionally, it
must be pointed out that the intensity of that part of the emission spectrum
attributed to the Ir(III) complex has a higher intensity in combination to the
nanoparticles as compared to the pure material. The CdSe(ZnS) particles with
sizes around 1 nm, as used in this study, were covering gold nanoparticles of 5 nm
Figure 9.47 Comparison of the
photoluminescence spectra of an Al 2 O 3 /
pyrene/PMMA nanocomposite as a powder and
suspended in methanol. For the powder, the
particles are close together, and therefore the
excimer spectrum is emitted. In the methanol
suspension with a low particle concentration,
the distance between particles is large and
therefore the probability for interaction is small.
In such a diluted suspension, the molecule
spectrum is emitted.
Figure 9.48 Absorbance of the Ir(III) complex
(as described in the text) and
photoluminescence spectrum of CdSe(ZnS)
nanoparticles. The emission maximum of the
nanoparticles is close to the maximal
absorption of the Ir(III) complex. Therefore, the
emission of CdSe(ZnS) nanoparticles excite the
Ir(III) complex in a nanocomposite [36].
9.6 Special Luminescent Nanocomposites j249