Isolated Adsorbates

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Isolated Adsorbates

• James G. Kushmerick

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Outline

• Experimental Overview
• Adsorption Dynamics
• Catalytic Activity
• Vibrational Spectroscopy

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STM Basics

• The STM maps a convolution of a surfaces
  electronic and topographic features

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STM Schematic
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Electronics Schematic
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UHV Chamber and Acoustic Isolation Room
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Adsorption Dynamics of Benzene on Ni110 at 4K
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Dosing Procedure
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Adsorption Trajectory
278Å x 278Å 50pA 20mV
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Accommodation Length
356Å x 214Å 50pA 20mV
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Adsorption Site Distribution
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Spectroscopy of Ni and Co on MoS2
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MoS2

• Naturally Occurring Mineral (Molybdenite)
• Metal Dichalcogenide MX2 (MGroup IVB, VB or
  VIB metals XS, Se, Te)
• Hydrodesulfurization Catalyst
• Intrinsic Semi-Conductor

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Atomic Resolution Image of MoS2 _at_ 77K75Å x 75Å
-1V 300pA
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3D Representation of MoS2 _at_ 77K45Å x 45Å -1V
300pA
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Experimental I/V and DOS of MoS2
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Negative Differential Resistance
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MoS2 Ring Structure
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Tip Assisted Diffusion of Ni on MoS2 _at_ 4K
AI091897.039 AI091897.040 AI091897.041 2
50Å -1.5V 100pA 200Å -1.5V 100pA 150Å -1.5V
100pA
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Contrast Reversal of Ni on MoS2
AI092397.015 AI092397.016 60Å -2V
200pA 60Å 2V 100pA
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Inelastic Electron Tunneling Spectroscopy with a
STM
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Elastic and Inelastic Tunneling
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I/V and dI/dV
V h?/e
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Experimental Arrangement