Source:http://linkedlifedata.com/resource/pubmed/id/17429945
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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
10
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| pubmed:dateCreated |
2007-5-14
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| pubmed:abstractText |
Evanescent-wave cavity ring-down spectroscopy has been applied to a planar fused-silica surface covered with crystal violet (CV+) cations to characterize the silanol groups indirectly. A radiation-polarization dependence of the adsorption isotherm of CV+ at the CH3CN/silica interface is measured and fit to a two-site Langmuir equation to determine the relative populations of two different types of isolated silanol groups. CV+ binding at type I sites yields a free energy of adsorption of -29.9 +/- 0.2 kJ/mol and a saturation surface density of (7.4 +/- 0.5) x 10(12) cm(-2), whereas the values of -17.9 +/- 0.4 kJ/mol and (3.1 +/- 0.4) x 10(13) cm(-2) are obtained for the type II sites. The CV+ cations, each with a planar area of approximately 120 A2, seem to be aligned randomly while lying over the SiO- type I sites, thereby suggesting that this type of site may be surrounded by a large empty surface area (>480 A2). In contrast, the CV+ cations on a type II sites are restricted with an average angle of approximately 40 degrees tilted off the surface normal, suggesting that the CV+ cations on these sites are grouped closely together. The average tilt angle increases with increasing concentration of crystal violet so that CV+ cations may be separated from each other to minimize the repulsion of nearby CV+ and SiOH sites.
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| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:status |
PubMed-not-MEDLINE
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| pubmed:month |
May
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| pubmed:issn |
0003-2700
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| pubmed:author | |
| pubmed:issnType |
Print
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| pubmed:day |
15
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| pubmed:volume |
79
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
3654-61
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| pubmed:year |
2007
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| pubmed:articleTitle |
Characterization of two types of silanol groups on fused-silica surfaces using evanescent-wave cavity ring-down spectroscopy.
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| pubmed:affiliation |
Department of Chemistry, National Taiwan University, and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan.
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| pubmed:publicationType |
Journal Article
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