Size/Shape – Property Relationships of Non - Carbonaceous Inorganic Nanoparticles and their Environmental Implications - Environmental and Human Health Impacts of Nanotechnology - page 95

Figure 3.7 TEM images of (A) initial CdSe (diameter 4.2 nm), (B) Ag 2 Se transformed from
the forward cation exchange reaction and (C) recovered CdSe nanocrystals from the reverse
cation exchange reaction. (D to F) XRD patterns, fl uorescence emission and optical absorp-
tion spectra of initial CdSe (top diffractogram or spectrum), Ag 2 Se (middle) and recovered
CdSe (bottom) nanocrystals, respectively. In the recovered CdSe, the peak positions of the
emission and absorption show a slight red shift from those of the initial CdSe, which becomes
negligible for nanospheres larger than 6 nm in diameter. An additional fl uorescence emission
feature near 700 nm seen in the recovered CdSe (E) is due to the increased surface trap
emission. Vertical lines in (E) and (F) are a guide for the comparison of peak positions. (Figure
and caption from Son et al. (2004), Science , 306 , 1009-12. Reprinted with permission from
AAAS.)