Deuterium NMR relaxation studies of liquids in confined geometries

Nuclear magnetic resonance (NMR) has been employed to study the confined geometry effects on reorientational dynamics of molecular liquids in porous media. The relative role of the pure geometrical confinement and the strength of the surface effect is investigated. The deuteron NMR spin-lattice relaxation times, T$\sb1$, of several molecular liquids in porous silica glasses are reported as function of pore size in the range from 17A to 143A over the temperature range from 260K to 310K. Molecular liquids studied include strongly interacting polar liquids such as pyridine-d$\sb5$, aniline-d$\sb5$ and nitrobenzene-d$\sb5$ whereas the saturated cyclic hydrocarbon liquids of cyclohexane-d$\sb{12}$ and cis-decalin-d$\sb{18}$ represent the weakly interacting liquids. In a first approximation, toluene-d$\sb1$ and dioxane-d$\sb8$ are chosen as examples of liquids with intermediate interactions with the silica surface. The experimental relaxation data are analyzed by using the two-state fast-exchange model which is found to be valid for the strongly interacting liquids and liquids with intermediate interactions. In terms of this model, the viscosity of the surface layer for pyridine-d$\sb5$ is about 30 times higher than that for bulk liquid pyridine. The importance of two-dimensional approach to describe motional dynamics of liquids confined to pores smaller than 30A is illustrated for liquid nitrobenzene-d$\sb5$.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Liu, Guoying

Contributors dc:contributor

• Jonas, Jiri

• Chemistry, Physical

Statement dc:rights

• Copyright 1991 Liu, Guoying

Language dc:language

eng

Identifier

AAI9210899
(UMI)AAI9210899

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/21494