Article,
Surface studies on the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate using X-ray photoelectron spectroscopy (XPS)
ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS, 220 (10-11): 1439-1453 (2006)
DOI: {10.1524/zpch.2006.220.10.1439}
Abstract
Surface studies of ionic liquids are particularly important for all
kinds of multiphasic operations employing ionic liquids, e.g. biphasic
homogeneous catalysis or supported ionic liquid phase catalysis. Using
X-ray photoelectron spectroscopy (XPS), the surface composition of the
model system 1-ethyl-3-methylimidazolium ethylsulfate
EMIMEtOSO3 was investigated. By comparing two different samples
of this ionic liquid from two different origins, we observed a decisive
influence of silicon containing impurities on composition and structure
of the surface. For the case of the impurities containing ionic liquid,
our angle-dependent XPS data are in agreement with a model of a surface
layer consisting of highly oriented ionic liquid molecules. From a
fundamental point of view, our study may be of general relevance for
the understanding, of the chemistry of liquid surfaces in general.
