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- Scanning Tunneling Microscope
Description of services:
- Determine local electronic structure and morphology of the sample, providing information with atomic resolution
- STM can be done at ambient conditions (atmospheric pressure and temperature), at the solid-liquid interface, in ultra-high vacuum and at helium temperatures, and at high pressure and high temperatures.
About the Scanning Tunneling Microscopy
Scanning Tunneling Microscopy (STM) is based on a principle of quantum mechanical tunneling of electrons from the sample to the scanning tip (or reverse). During a measurement, the tip and the sample are not in mechanical contact, but are separated by a gap smaller than 1 nm. Due to the short distance there is a finite probability of electron tunneling through the gap, with the help of an applied bias. Positive bias electrons tunnel from the tip into the sample, and reverse for negative bias. For semiconductors, that will correspond to probing unoccupied and occupied states respectively. Thus measured tunneling current (I) is a function of applied bias (U) and tip-sample separation (h)
I ~ U Ae-bh
STM can be done routinely at ambient conditions (atmospheric pressure and temperature), at the solid-liquid interface, in ultra-high vacuum and at helium temperatures, and at high pressure and high temperatures. The latter is particularly useful for operando studies (ASCAT- Operando STM) of model catalysts and can be done in a unique system ReactorSTM installed in Oslo in June 2016.
The reactor STM is an STM instrument (one of 5 world-wide), capable of measuring surfaces at atomic resolution at a video rate speed and at industrially employed conditions of 1-5 bar gas pressure and up to 600 K temperature.
Currently there are two projects running on the Reactor STM: the study of Ammonia Slip 2D model CATalysts (Ammonia Slip Catalysts (ASCAT) - Operando STM), and the NOx abatement project.
The Reactor STM is produced by: LPM- Leiden Probe Microscopy B.V.