FTIR matrix isolation and ab initio investigations of the Si2N and BNSi molecules
作者:G Meloni、S Nunziante Cesaro、N Sanna
DOI:10.1016/s0009-2614(01)00663-7
日期:2001.7
were analyzed by FTIRmatrixisolation technique. An absorption at is assigned as the antisymmetric stretching mode of the symmetric linear molecule SiNSi, in good agreement with ab initio calculations. A pair of doublets in the absorption spectrum at and are assigned to the and stretching modes of the linear BNSi molecule, on the basis of the relative intensities of the isotopic features. Again, these
Nitrogen-Containing Paramagnetic Centers in Vitreous Silica
作者:V. A. Radtsig
DOI:10.1007/s10975-005-0112-x
日期:2005.7
The results of a study on the structure and spectral characteristics of nitrogen-containing paramagnetic defects in vitreous silicas are presented. The UV irradiation, γ-irradiation, and mechanical destruction of nitrogen-doped vitreous silicas, which were synthesized using a plasma-chemical SPCVD technology, were used for the generation of paramagnetic centers. Another technique for producing nitrogen-containing paramagnetic centers was the target-oriented chemical modification of the surface defects of silica with the use of NH3 (ND3) molecules. Paramagnetic centers with free valences at silicon [(≡Si-O-)2Si· (-NH2) and (≡Si-O-)2Si· -N(-Si≡)2] and nitrogen atoms [≡Si-N· -H and ≡Si-N· -Si≡] were detected. The reactivity of nitrogen-centered radicals toward H2 and CO molecules was studied. Quantum-chemical calculations of model systems were employed in the interpretation of the experimental data. The strengths of Si-O and Si-N bonds in vitreous silica were compared.