Characterization
Silica particles were prepared using a sol–gel process
with a sequential addition technique in an ultrasonication
bath. Various types of experiments were conducted in which
the concentration of one reagent was fixed and the concentration
of other reagents were changed one by one.
Particle sizes were measured using field emission scanning
electron microscopy (FE-SEM, JEOL, F 6500, Japan).
Clean glass capillaries were used to transfer a droplet of each
sample of suspension to highly oriented pyrolitic graphite
(HOPG). The samples were allowed to dry and then micrographs
were taken at a number of random locations on the
grid. The size of the particles was calculated from the SEM
pictures using an average of 100 to 200 particles in almost
all cases. The electronic absorption behavior was analyzed
using a UV PC spectrophotometer (Shimadzu 3100).