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Nanostructural and Chemical Characterization

In-Situ Characterization

Lehigh University has the premier in-situ molecular characterization laboratory in the world, employing the optical methods of Ransighman, IR and UV-Vis-NIR DRS spectroscopies, for investigating nanoscale metal oxide catalytic materials. The fundamental goal of these facilities is to establish the relationship of molecular structure, reactivity, and selectivity that are the basis for the molecular engineering of nanoscale metal oxide catalysts for applications in many fields such as environmental, energy and petrochemicals.




Analytical Electron Microscopy
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The Vacuum Generators HB 603 Scanning Transmission Electron Microscope. This unique dedicated STEM operates up to 300kV. It is equipped with two EDS systems: one with a standard Si(Li) detector and one with an intrinsic Ge detector. Configured with an optimum geometry and large solid angles of collection. This makes our instrument the world leader for high resolution EDS and EELS analysis.

STEM-XEDS elemental maps from Au-Ag core-shell nanoparticles.


This AEM micrograph shows a nanostructure X-ray map of Yttrium segregation to grain boundaries in a Y-doped ZrO2 ceramic. The field of view is 300 x 300 nm^2


STEM-ADF image

Ag map (Ag La)


Au map (Au La)




Surface Chemical Analysis Back to Top
The angle resolved XPS Scienta ESCA-300 is a unique high resolution, high sensitivity instrument for analysis of the nanochemistry of surfaces. The Scienta has a rotating anode and monochromatized electron gun with a low energy electron diffraction/residual gas analyzer. It operates in the range of -175 C to > 600 °C, UHV to one atmosphere.




In-situ Molecular Characterization of Nanooxides Under Different Temperature, Pressure, and Gaseous/Liquid Environments
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Optical Molecular Spectroscopies

Laser Raman Spectroscopy (Structure of Metal Oxides, as small as 0.4 nm)
Infra Red Spectroscopy (Complementary to Raman)
UV-VIS Spectroscopy (Oxidation States of Metal Oxides, as small as 0.4 nm)



Transmission Electron Microscopy Back to Top
The JEOL 2200FS is a 200kV FEG-TEM/STEM fitted with a Cs aberration corrector to achieve an ultimate probe-size of 0.15nm and maximize the spatial resolution of the image and spectroscopic data. It is equipped with XEDS and EELS systems. It also has a novel in-column Omega-filter to allow energy filtering of images and diffraction patterns. This instrument has the best resolution and a full remote access capability.
Size selected sintering of a bimodal array of self-organized gold nanoparticles observed in the JEOL 2200FS



Lattice Imaging of Nanoparticles Back to Top
A rhodium catalyst nanoparticle supported on cerium oxide:

Experimental HREM image

Simulated HREM image

Structural model



Focused Ion Beam Thinning
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FEI Strata DB 235; a dual-Beam FIB is a combination of a scanning electron microscope (SEM) with a focused ion beam system (FIB). It is used for preparing TEM samples from specific localized areas and the nanopatterning of substrates.
Stages of preparation of piezoelectric ceramic TEM-foil



Optical Spectroscopy and Luminescence Microscopy of Nanostructures
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Ferroelectric domain engineering

The spatial resolution of a confocal microscope and near field optical microscope with the high spectral resolution and selectivity offered by combined excitation-emission spectroscopy allows correlation of atomic scale defects with optical properties observed on the nanoscale. Domains in a confocal luminescence microscope (contrast is obtrained through changes in the atomistic defect structure that also determine mobility, shape of the domains and the voltage required for domain switching).

 

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