The method produces 12 ± 2 nm particles. The plasmon absorbance
is near 400 nm and the peak width at half maximum
(PWHM) is 50–70 nm. How the student experiment
was developed is described below in detail, including the use
of transmission electron microscopy (TEM) to find the size
of particles that corresponded to the visible spectrum of the
product. (Depending on the availability of the instrument,
the TEM material could be expanded in an experiment for
an upper-level course.) The relationship between aggregation
and optical properties was determined along with a method
to protect the particles using polyvinylpyrrolidone. Results
obtained in two general chemistry laboratory classes (25 student
pairs) are given along with student reactions to the experiment.