PHYS01200704032 Debes Ray - Homi Bhabha National Institute

Absorbance
Integrated Absorbance / Yield
Chapter 4: Optimization of the Block Copolymer-mediated Synthesis of Gold Nanoparticles
and is shown in the inset of Figure 4.4(a). The nanoparticles have a mean size of about 12
nm. Further, Figure 4.4(b) shows TEM image of gold nanoparticles for the system of
1 wt% P85 at one of the higher gold salt concentrations (0.016 wt% HAuCl 4 .3H 2 O)
indicating formation of both non-spherical and polydispersed nanoparticles and thus
consistent with the SPR data [Figure 4.3(a)] observed for such systems.
0.7
150
0.6
100
0.4
50
0
t s
10 100 1000
Time (min.)
0.2
0.0
400 500 600 700 800
Wavelength (nm)
Figure 4.5. Time-dependent UV-visible absorption spectra of 1 wt% P85 with 0.008 wt%
HAuCl 4 .3H 2 O. The different data sets from bottom to top correspond to increase in the
absorbance with time. Inset: The variation of the integrated absorbance of SPR peak as a
function of time.
Figure 4.5 shows the time-dependent UV-visible spectra recorded during the
synthesis of gold nanoparticles for 1 wt% P85 with 0.008 wt% HAuCl 4 .3H 2 O over a long
period of time (up to 16 hrs). After these two components are mixed, the formation was
monitored with an initial interval of 5 minutes for about 4 hours and afterwards with a period
of 30 minutes. Data show that nanoparticles start forming with the mixing as seen through the
building of SPR peak. The peak intensity increases with time and gets saturated at about 60
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