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Image of the Month
Posted Date: February 1, 2011
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Porphyrin derivatives are promising candidates for the generation of functional molecular architectures on surfaces. The unambiguous identification of individual porphyrin species is a prerequisite in this regard. We investigated a layer of intermixed tetraphenylporphyrins (TPP), namely 2HTPP, FeTPP and CoTPP at room temperature. Voltage-dependent STM imaging was successfully applied to discriminate the very similar porphyrins. The characteristic appearance of CoTPP at low negative voltages (>-0.4 V) can be traced back to a specific interaction of the Co dz2 orbital with the underlying Ag substrate. The dumbbell appearance observed for FeTPP over a wide bias range and for CoTPP at lower negative voltages (<-0.4 V) is in line with the well known saddle shape of the porphyrin macrocycle in the adsorbed state.

Microscope:
UHV300 VT

Controls:
RHK SPM 100

Contributors:
F. Buchner, K.-G. Warnick, T. Wölfle, A. Görling, H.-P. Steinrück, W. Hieringer and H. Marbach – Universitat Erlangen-Nurnberg

Reference:
J. Phys. Chem. C 2009, 113, 16450–16457

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Image of the Month
Posted Date: January 1, 2011
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Raw images showing the friction signal in the left-to-right sliding direction. Upper row: 4-layer graphene; lower row: bulk graphite; right column: Low-pass filtered images of the friction measurements showing the periodicity of the lattice. Black dots represent the periodic sites of the friction force signal. The scale bars correspond to 0.5 nm.

Microscope:
UHV350

Controls:
RHK SPM 100

Contributors:
Q. Li and R.W. Carpick, University of Pennsylvania

Reference:
Science 328, 76 (2010) DOI: 10.1126/science.1184167

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Image of the Month
Posted Date: August 1, 2010
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RHEED intensity oscillation monitored on the specular spot during the growth of the LSMO on STO substrate at 900 °C. Inset a1 and a2: RHEED pattern obtained before and after deposition, respectively. (b) Resistivity/magnetization vs temperature curves for LSMO thin films of 5 nm thickness. STM topographic images (1×1 um2) with set point (sample bias 0.7 V, current 0.5 nA) taken at (c) 300 K and (d) 105 K.

Reprinted with permission from Abhimanyu Rana, Kashinath Bogle, Onkar Game, Shankar Patil, Nagarajan Valanoor, and Satishchandra Ogale, APPLIED PHYSICS LETTERS 96, 263108 2010. Copyright 2010, American Institute of Physics.

Microscope:
UHV3500 VT with Variable Magnetic Field

Controls:
RHK SPM 100

Contributors:
Abhimanyu Rana, Kashinath Bogle, Onkar Game, Shankar Patil, Nagarajan Valanoor, and Satishchandra Ogale – NCL, Pune and Univ. of New South Wales

Reference:
APPLIED PHYSICS LETTERS 96, 263108 (2010)

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Image of the Month
Posted Date: July 1, 2010
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STM image of organometallic structures formed when dosing phenyl diisocyanide (PDI) on a reconstructed Au(111) surface. The chains that originate at the gold atoms island indicated by the white dash line resemble the shape of a “Nano Spider”. The molecules were dosed from a kundsen type source as described in the following link:
LINK

Imaging conditions: Scan size: 20nm x 20nm. Image taken at room temperature with a tunneling current It=206pA and a sample bias voltabe Vb=-2.0V

Microscope:
UHV750 STM/AFM scan head

Controls:
RHK SPM 100

Contributors:
Jorge A. Boscoboinik, Florencia C. Calaza and Wilfred T. Tysoe. Department of Chemistry and Biochemistry, University of Wisconsin Milwaukee

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