Silica Gel Surface: Molecular Dynamics of Surface Silanols
| Autor: | Takeshi Kobayashi, Gary E. Maciel, and Joseph A. DiVerdi |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Deuterium NMR
Silica gel Inorganic chemistry medicine.disease Surfaces Coatings and Films Electronic Optical and Magnetic Materials Molecular dynamics Silanol chemistry.chemical_compound General Energy Deuterium chemistry Proton NMR medicine Physical chemistry Dehydration Physical and Theoretical Chemistry Spectroscopy |
| Zdroj: | The Journal of Physical Chemistry C. 112:4315-4326 |
| ISSN: | 1932-7455 1932-7447 |
| Popis: | The molecular dynamics of the silanols of high surface-area silica gel was studied using solid-state deuterium NMR spectroscopy. Deuterated silica gel samples were prepared by replacement of the exchangable silanol protons upon exposure to liquid 2H2O and subsequent dehydration under vacuum at various temperatures that were selected to provide samples with varying populations of specific surface features, including (a) “isolated” silanols, that is, those that are not hydrogen-bonded (as demonstrated by the 1H NMR chemical shift), (b) hydrogen-bonded silanols with a wide range of hydrogen-bonding strengths (as shown by the broad 1H NMR peak), and (c) a hydrogen-bonded network of physisorbed water. On a highly dehydrated surface obtained by dehydration at 500 °C and containing only isolated silanols, analysis of the deuterium line shapes indicates that the “isolated” silanols exhibit a broad, inhomogeneous distribution of librational amplitudes of O−H entities about the internuclear Si−O vector, all in the ... |
| Databáze: | OpenAIRE |
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