Photoluminescence spectrum of biogenic AgNPs is shown in
Fig. 6(B), when excited with 350 nm depicts the maximum
emission peak at 449 nm, describing the photoluminescent nature.
It is worth to note that the photo emission wavelength is independent
of the particle size. This visible luminescence phenomenon of
silver is due to excitation of electron from occupied d bands into
states above the Fermi level (f-level) with substantial electron–
phonon and hole-phonon scattering process resulting in energy
loss and photoluminescence radiative recombination of electrons
from an occupied sp-band with the holes