a1 Department of Chemical Engineering and Materials Science, University of California, Davis, One Shields Ave., Davis, CA 95616, USA
a2 Department of Molecular and Cellular Biology, University of California, Davis, One Shields Ave., Davis, CA 95616, USA
a3 Department of Physical and Life Sciences, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
Observation of growth, synthesis, dynamics, and electrochemical reactions in the liquid state is an important yet largely unstudied aspect of nanotechnology. The only techniques that can potentially provide the insights necessary to advance our understanding of these mechanisms is simultaneous atomic-scale imaging and quantitative chemical analysis (through spectroscopy) under environmental conditions in the transmission electron microscope. In this study we describe the experimental and technical conditions necessary to obtain electron energy loss (EEL) spectra from a nanoparticle in colloidal suspension using aberration-corrected scanning transmission electron microscopy (STEM) combined with the environmental liquid stage. At a fluid path length below 400 nm, atomic resolution images can be obtained and simultaneous compositional analysis can be achieved. We show that EEL spectroscopy can be used to quantify the total fluid path length around the nanoparticle and demonstrate that characteristic core-loss signals from the suspended nanoparticles can be resolved and analyzed to provide information on the local interfacial chemistry with the surrounding environment. The combined approach using aberration-corrected STEM and EEL spectra with the in situ fluid stage demonstrates a plenary platform for detailed investigations of solution-based catalysis.
(Received August 03 2011)
(Accepted January 10 2012)
p1 Present address: Pacific Northwest National Laboratory, Richland, WA 99354, USA