describes a mechanism, expressed by a mathematical description, that is fundamentally different from the quantum confinement phenomena in semiconductor
quantum dots. All mechanisms of blue shift – except for this one – show, in contrast
to that observed with oxide/polymer nanocomposites, a negative exponent of the
particle size. The blue shift of the luminescence emission of oxide/m-PMMA
nanocomposites exhibits the positive exponent 3. l
À1 ¼ l
À1
0 þ bd
3
Similar to the blue shift with decreasing particle size, a reduction in the linewidth
at half-maximum intensity with decreasing particle size was observed [12,18].
Figure 9.26 Dependency of luminescence
intensity and wavelength maximum of ZrO 2 /
PMMA nanocomposites as a function of
particle size. To show the dependencies, these
graphs are rectified. (a) Luminescence intensity
of ZrO 2 /PMMA nanocomposites as a function
of inverse particle size following Eq. (9.10). The
proportionality with d
À1 indicates a
proportionality of the intensity to the surface of
the particles. (b) Wavelength maximum of
ZrO 2 /PMMA nanocomposites as a function of
particle size. The mathematical description
underlying this graph l
À1 ¼ l
À1
0 þ bd
3 is
fundamentally different from that for quantum
confinement. In contrast to all other
mechanisms of blue shift, this shows a positive
exponent of the particle size.
230j 9 Optical Properties of Nanoparticles