The influence of five different chemical pretreatments on the optical properties of the Si surface was investigated by means of nulling ellipsometry. The ellipsometric data are fit to an air-SiO2-interface-Si model. The results of the experimental data interpretation show that thickness and structure of the "interracial layer" are changed drastically: the interracial layer thickness increases and the interracial layer optical properties approach the optical properties of crystalline Si. These changes in the interracial layer indicate the crystalline structure improvement of the substrate surface.

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Si(100) surfaces were modified by means of enhanced RCA procedure with “ HBF4-last” and “HF-last”. Nulling ellipsometric (NE) and secondary ion mass spectrometric (SIMS) measurements revealed that HBF4-treated Si surface is more strongly passivated by hydrogen and fluorine than HF-treated one: the oxidation rate of the HBF4-treated Si surfaces in air was found to be lower than that of the HF-treate surface. Scanning tunneling microscope (STM) images of HBF4-cleaned surface after 18 h storage in air were quite stable during observation, scanning could be easily performed over a wide area on every plot we chose.

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The effects of silicon dioxide-based nanoparticles on the viability and proliferative activity of human peripheral blood cultured lymphocytes were studied. All nanoparticles in a concentration of 100 μg/ml produced a significant cytotoxic effect, its intensity depending on particles' structure: SiO2 nanoparticles were least toxic, while Ce3(+)-intercaled montmorillonite nanoparticles were most toxic. The cells died mainly by apoptosis and postapoptotic necrosis. Incubation with nanoparticles in a concentration of 100 μg/ml for 72 h caused death of all phytohemagglutinin-activated lymphocytes, while in concentrations of 1 and 10 μg/ml the nanoparticles had no effect of proliferative activity of cells. The results suggest that the effects of nanoparticles on cells are determined by the nanoparticle concentration and size, as well as by their structure.