Lead oxide after illumination

UV irradiation leads to an increase in the intensity of the Si—O stretching bands and the H-Si-Os deformation and stretching bands [236, 251]. This is typical of photooxidation of PS [217]. The decrease in intensity of these four bands after etching in HF indicates the formation of an oxide layer under UV illumination. Its appearance is also accompanied by a reduction in the intensity of all Si-H bands (664, 906, 2087, 2106, and 2140 cm ). Figures 5.24 and 5.25 show the increase of oxide bands and the decrease of SiH bonds upon UV illumination of the PS layer [236, 251]. 

The electron transfer processes described above lead either to a photooxidation or -reduction of the excited molecules. Since only adsorbed molecules participate in the electron transfer reaction, it would be expected that all adsorbed molecules are oxidized or reduced after a certain illumination. 

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