Each sample was measured with a Philips CM 20 TEM operated at
200 kV to determine the size of the silver or copper NPs. The pictures
in Fig. 8 show the NPs.
Size dispersion of the NPs population is rather homogeneous with
a diameter of a few nanometers. The depth field does not allow to
evaluate a fill factor. The red glass containing copper was measured
in the same conditions (Fig. 9).
This copper exchanged glass consists in few bigger NPs with a
diameter in a range diameter of 25 to 40 nm and do not form a significant
population. We suggest a contrast change into the NPs which
could be assigned to an optical effect due to a strong optical contrast
or a core-shell composition with a 15 nm core diameter, however the
copper nature of the TEM source did not allow to obtain highresolution
picture and the structure identification.