Proton dynamics and surface heterogeneity of silica gel with adsorbed benzene below one monolayer coverage
Proton and deuteron NMR relaxation times of C/sub 6/H/sub 6/, C/sub 6/D/sub 6/, and mixtures of these molecules have been measured on a superpure silica gel (SPSG) and a sample of a Matheson silica gel (MSG) both dehydrated at 600/sup 0/ C and rotational (intramolecular) and translational (intermolecular) correlation times have been computed from the relaxation time data at a statistical coverage theta=0.6. Three kinds of adsorption sites have been observed: (1) A sites, which are probably oxygen vacancies on the surface, (2) B sites which are assigned to paired hydroxyl groups on the surface, and finally (3) C sites which comprise 80% of the occupied surface and are primarily isolated hydroxyl groups. Rotational and translational motions are highly correlated for the A and B site molecules. The mean number of molecules clustered at the A and B sites are inferred from the intermolecular second moments associated with each of these sites. The surface density of the A sites is 1.1 x 10/sup 12/ cm/sup -2/ for SPSG and 3.1 x 10/sup 12/ cm/sup -2/ for MSG.
- Research Organization:
- Argonne National Laboratory, Argonne, Illinois 60439
- OSTI ID:
- 6480813
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 70:7
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
SILICA
NUCLEAR MAGNETIC RESONANCE
SORPTIVE PROPERTIES
BENZENE
DEUTERONS
EXPERIMENTAL DATA
GELS
ISOLATED VALUES
PROTONS
RELAXATION
SURFACES
AROMATICS
BARYONS
CHALCOGENIDES
CHARGED PARTICLES
COLLOIDS
DATA
DATA FORMS
DISPERSIONS
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HYDROCARBONS
INFORMATION
MAGNETIC RESONANCE
MINERALS
NUCLEONS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
RESONANCE
SILICON COMPOUNDS
SILICON OXIDES
SURFACE PROPERTIES
400201* - Chemical & Physicochemical Properties
400301 - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)