Abstract:
Metallic aggregates in colloidal phases or supported aggregates attract increasing
attention of researchers because of the wide range of possible applications (catalysis,
environment, non-linear optics, biology and medicine). Radiolysis ranks among the most
effective methods for the reduction of ions, giving the possibility of synthesis of aggregates of
atoms. It is a powerful method to control the size of the particles, their location on the surface
or volume.
In the first part of this work, the morphological and structural properties of silver
aggregates supported on silica were studied. X-ray diffraction identified the Ag6Si2O7 phase
for different Ag+ ion charges as well as heat-treated samples. The FTIR spectroscopy study of
Ag/SiO2 samples revealed the vibrations of Si-O-Si, Si-OH, Ag-O and Ag-SO4 bonds at the
respective wave numbers 468, 810, 615 and 641 cm-1. The study of the optical properties of
Ag/SiO2 nanoagreggates by UV- visible spectrophotometry showed the presence, in addition
to a broadband in the visible range, three peaks in the UV domain. After reduction under
hydrogen, the metal Ag phase of nanometric size was identified by XRD.
In the second part, we studied, by time-resolved pulse radiolysis, nickel clusters in
suspension. The formation of Ni+ ions and then those of nickel atoms was observed. The
ionizing radiation generation of nickel aggregates in solution was observed for the first time
live during this work.
