Spatially Resolved and Atom Specific Microscopy and Spectroscopy

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Spatially Resolved and Atom Specific Microscopy
and Spectroscopy

• New Characterization Tools
• What can we do now that we could not do before
  and how will it change the world

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Complementarity of techniques
Insight ? NN where N number of tools We want
everything at once!
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Real-time surface imaging methods

• Nanoscale atomic resolution
• Fast Scanning Tunneling Microscopy (STM)
• Field Ion Microscopy (FIM/FEM)
• Mesoscale chemically sensitive
• Low Energy Electron Microscopy (LEEM)
• Photoemission Electron Microscopy (PEEM)
• Ellipsomicroscopy for Surface Imaging (EMSI)
• Imaging FT-IR spectroscopy

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Pattern formation on catalysts
J. Lauterbach, et al., Surface Science 294
(1993) 116
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Ellipsomicroscopy for Surface Imaging (EMSI)
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P gt 10-3 mbar -gt EMSI
T 540 K, CO/O2 0.11. Image size1mm x 1.25
mm, dt 0.33 s
Video
Lele, T. and J. Lauterbach, Chaos 12(1) (2002)
164-171.
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Low Energy Electron Microscopy
Synchrotron-based Photoemission Electron
Microscopy
RuO2 growth
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Probing of Valence Electrons with X-rays
Atom specific Orbital symmetry
selective Experiment--Theory
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Catalytic Chemistry with Orbitals
Haber-Bosch N2 3H2 2NH3
Hansen et.al. Science 294, 1508 (2001)
New Ru Catalyst Active site at steps
Probe pulse at different delay time Dt
Theoretical simulations, Mats Nyberg, Stockholm
University
Both N atoms
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XASpectroelectrochemistry

• Element specific
• Resolves multiple redox sites
• Perfect for fuel cells

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New Tools for Neutron Scattering

• Parallel detectors offer more sensitivity
• Vibrational spectroscopy without selection rules

Determination of Chloroform Adsorption site in
Faujasite From H pair distribution
function. (J. Eckert, C. Mellot-Draznieks and A.
K. Cheetham, J. Am. Chem. Soc. 2002, 124, 170 )
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Atomic Resolution Images Under High Pressure
Conditions
Pressure-induced reconstructions on Cu(110)
exposed to H2
Laegsgaard, Osterlund, Thostrup, Rasmussen,
Stensgaard and Besenbacher , Rev. Sci. Instrum.
72 (2001), 3537-3542.
In-situ HRTEM offers defect analysis -
identification of active sites in vanadyl
pyrophosphate catalysts
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Z-contrast STEM




Z31
Z33
Ga
As

1.4Å


EELS
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EELS profile across a single particle
2nm
Co/Ni Concentration profile
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Imaging of Active Catalyst Atom Configurations
g
g
Pt on
-alumina
Pt on
-alumina
0.5 Å probe
1.3 Å probe
Pt atoms sit in surface vacancies