The French partner aims at understanding the vapor deposition growth
and morphological behavior of metallic nanometer-size islands on oxide
supports. Motivated by industrial applications, two main research
directions of are developed:
- the understand ing of wetting at metal/oxide interfaces;
- the problem of gas adsorption and oxidation in the
framework of heterogeneous catalysis.
However, in situ studies of the growth process itself or gas exposure
are rather challenging since non-invasive and real time methods are
required. Instead of using time consuming near field imaging
technique, this team has developed of a know-how of optical
characterization through the excitation of plasmon resonances inside
the nanoparticles. With Surface Differ ential Reflectivity Spectroscopy
(SDRS), the relative change of the sample reflectivity is recorded in
the UV-visible range as function of time, and even with sub-monolayer
sensitivity. By a comparison with in situ small angle X-ray
scattering, the group demonstrated the optical techniques have the
potential of giving good precision for the overall morphology if
spectra are analyzed with suitable models. The idea is to go beyond
the limitations of the previously developed GranFilm software and to
revive a previous collaboration on the theory of optical properties of
granular layers in the light of new experimental developments in the
Paris group. The Norwegian partner brings the needed background in
electromagnetic simulations and the French group the ex perimental
questioning. Two original directions involving theoretical development
and numerical implementations are foreseen during this project:
- calculating the optical response of core-shell particles,
- handling theoretically the size distrib ution found in the real samples.
The final goal is to have a freely available numerical simulation tool
that could suit to the experimental needs in terms of calculation of
optical Fresnel coefficients.