Nitrogen in Silica

Paramagnetic centers with an unpaired electron localized on the three-coordinated silicon atom are formed in vitreous silica under exposure to various factors [10,104,105]. In the presence of nitrogen atoms in glass, a portion of these atoms can occur as the (=Si-0-)2Si (-N ) structure. However, to the best of the author s knowledge, the occurrence of these centers in 

Radicals (=Si-0)2Si (NH2) were obtained as a product of the following two-step process that occurred on the surface of RSi (see Section 9.2 for details)  

The (=Si-0)2(H0)Si-N H PC was prepared from (=Si-0)2Si -(NH2) radicals using the following modification steps  

Point Defects on the Silica Surface Structure and Reactivity 321 

According to the results of calculations, the SiNSi2 fragment in the radical is planar, unlike the SiNH2 group in the F2Si-NH2 radical. Thus, the pyra-midality of the N atom decreases in the order NH3, (=Si-0)2Si -NH2, (=Si-0)3Si. NH(Si=)2 and N(Si=)3, and the last two members of this series are planar. 

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