Characterization of interfaces by elastic light scattering and profilometry

Sammanfattning: This thesis deals with the characterization of interfaces by elastic light scattering and profilometry. The sensitivity of scattering measurements to surface topography were used in two major ways. It was shown that surface reactions in a liquid-solid interface can be monitored in situ in terms of changes in surface roughness. A novel spectroscopic, in situ light scattering technique was used, together with in situ atomic force microscopy to study SnO2, and WO3 electrode surfaces subjected to adsorption and electrodeposition in a LiClO4/propylene carbonate electrolyte.In the case of thin film light scattering, the cross correlation between interfaces could be determined. This was applied to study the growth of oxides on metallic and transparent substrates. The use of an electrochromic WO3 film on a reflecting A1 substrate was found to be a promising method of controlling the relative contributions of the interfaces to the resulting scattering. Cu2O films, oxidized on Cu were shown to give uncorrelated interfaces, although the amplitude and the length scale of the roughness changed in the same way with film thickness for both interfaces. Sputtering of transparent SnO2 films with different film thickness onto rough glass substrates was shown to yield both smoothing and roughening effects upon the front surface of the film. It was found that the scaling of the surface roughness is different in regions of smoothing and roughening.The thesis also includes an investigation of the validity of the scalar scattering theory for IR-transmitting samples. The maximum ratio between the root-mean-square roughness and the wavelength of the light, to be used in scalar theory, was found to be considerably higher in transmittance than in reflectance. A procedure was introduced for obtaining the correct hemispherical reflectance and transmittance of anisotropically scattering samples in focusing Coblentz spheres. Finally, the design of semi-transmitting mirror coatings was considered. The international DVD standard for compact discs with improved storage capacity is based on a semi-transmitting mirror, that permits reading an opaque second mirror layer underneath.

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