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Interfacial Processes Group

Paul Fenter


In situ studies of mineral-fluid interfaces are performed using high
resolution X-ray scattering and spectroscopic techniques to achieve
a fundamental understanding of mineral-water interface structure
and reactivity. The atomic-scale structure of both the substrate and
near-surface fluid provides new insight into the equilibrium structure
of this interface as a function of solution composition. Compositional
changes are also observed directly in real-time during reactions to
reveal dynamic processes. Direct observation of these structural
changes leads to new insights into specific reaction mechanisms
at mineral-fluid interfaces.

Recent work includes direct in situ measurements of the hydration
layer structure at mineral-water interfaces, ion adsorption, silicate
dissolution, and more. See examples of our recent results, and a
complete list of publications. For more information contact
Paul Fenter.

Ongoing collaborations, including Neil Sturchio (Univ. of Illinois
at Chicago/ANL), Michael Bedzyk (Northwestern University/
ANL), Kathryn Nagy (Univ. of Illinois at Chicago), Michael
Machesky (Illinois State Water Survey), David Wesolowski (Oak
Ridge National Laboratory), Steve Sutton (GSE-CARS, Univ.
of Chicago) and others.



Synchrotron Radiation Studies at the Advanced
Photon Source

We have been making measurements at the Advanced Photon
Source (APS)
since 1997, using beamlines at the BESSRC and
other sectors. We primarily use X-ray scattering techniques,
including surface X-ray scattering (including X-ray reflectivity
and grazing incidence X-ray scattering), resonant anomalous
X-ray reflectivity
, and X-ray standing waves, and X-ray
standing wave imaging
. X-ray standing wave measurements
are performed on a spectrometer that we built and operate at
end-station 12-ID-D. In many cases, we perform complimentary
studies using atomic force microscopy (AFM) and/or X-ray
absorption spectroscopy.

The development and application of synchrotron X-ray
scattering techniques for in situ studies of mineral-fluid interfaces
is an important part of our research program. These developments
take advantage of the unique characteristics of synchrotron
radiation at the Advanced Photon Source (APS), including
temporal and spatial resolution afforded by the high APS beam
brilliance as well as the tunability of the X-ray photon energy
that allows for spectroscopic sensitivities. Fundamentally new
types of in situ experiments are possible for mineral-fluid interfaces,
especially microbeam and time-resolved scattering studies. These
experiments will further define kinetics and reaction mechanisms
at the atomic scale in key mineral-fluid systems, and will constrain
the continued development of theory pertinent to mineral-fluid
interface processes.

This research is funded by the Geosciences Research Program
of the DOE's Office of Basic Energy Sciences.

Recent Highlights



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Interfacial Processes

Radiation and

Biological Materials Growth Facility

Cluster Studies

Chemical Dynamics

Atomic Physics


Heavy Elements

Coordination Chemistry

f-Electron Interactions

Actinide Facility

Computational Materials and Electrochemical Processes

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