Nanoscale structural information underlies research aimed at fabricating catalysts in a more controlled way. Surface science methods can provide that information, but the complexity of heterogeneous systems in general hinders the application of these methods to their full potential. In the last decades, a solution to this problem has been found in the use of model systems, ranging from well-defined single crystals of the supported phase to films or particles of that phase on flat or spherical model supports. In this paper, we review the literature on the latter model systems, that is, particles on a model support. Attention is payed to both preparation and use of such model systems.

https://pure.tue.nl/ws/files/1495087/617871.pdf

Surface Science Approach to Modeling Supported Catalysts

For the modeling of infrared spectra it is a common approach to use a dielectric function that treats the vibrational modes as damped harmonic oscillators. This model was found to be rather crude for some applications to amorphous solids. A dielectric function model yielding a Gaussian shape of the absorption lines and satisfying Kramers–Kronig relations is suggested. The model function is constructed by a convolution of a Gaussian function with the dielectric function of the damped harmonic oscillator model. An analytical solution of this integral is given. It is demonstrated that this model describes the spectra of thermally grown ultrathin (1.3 nm) silicon oxide films, plasma‐deposited silicon films, plasma‐deposited silicon nitride films, and amorphous aluminum oxide films very well. The physical motivation of the dielectric function model suggested is the randomness of the vibrational frequencies in an amorphous structure.

L. Pietronero

Papers

Vibrational properties of Al 2 O 3 films on gold, aluminum, and silicon