TA2

 

The Microscopy group has accumulated particular expertise in

 

  • imaging and analysis in scanning transmission electron microscopy
  • electron energy loss spectroscopy
  • spatially resolved EELS in the Spectrum Imaging (SPIM) mode
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The laboratory will provide access to the UPS-TEM lab which is composed of the following instruments:

 

  •  SPIM-STEM: a dedicated STEM operating at 100 kV with a spacia resolution of 0.5 nm
  • SPIM-ultraSTEM: a novel dedicated STEM (presently under construction) with a 0.1 nm resolution and an energy resolution below 0.2 eV.

SPIM-COMP: a dedicated computer support providing tools for data processing.

 

 

Scanning TEM (STEM): VG 501

 

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An electron beam is focused on the surface of a specimen using various magnetic lenses, to form a high-brightness sub-nanometer incident probe (0.5-1nm). An image is generated by scanning the focused beam over the specimen. The most important advantage of a STEM is the possibility of collecting simultaneously different characteristic signals generated from the nano-volume defined by the diameter of the probe and the local thickness of the sample. This multidetection is possible thanks to the absence of important electronic optics after the sample. This specific design makes STEM a well-suited technique to characterise morphologically and chemically materials at the nanometer scale.
We commonly use the STEM to perform EELS, Electron Energy Loss Spectroscopy. The energy of scattered electrons are measured within an energy resolution of 0.3eV, their energy loss corresponding to characteristic interactions with the material. Coupled with the fine spacial resolution of the electron beam this allows us to, for example, produce chemical maps at sub-nanometre resolution.

 

 

High Resolution TEM (HRTEM): Akashi Topcon EM-002B

 

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A specified area of the sample is irradiated with an almost parallel electron beam and the scattered electrons are collected over a narrow solid angle and focused by the objective lenses onto the image plane. The elastically scattered electrons interfere with the unscattered electrons to produce a phase contrast image. Due to high coherence of the incident beam, the microscope delivers images with high spatial resolution (0.2 nm) allowing precise structural characterisation of the investigated object.  

 

 

Beowulf Cluster: 10 node dual processor P4 Linux system

 

 

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Full high level quantum mechanical calculations of materials properties at the nanometre scale requires substantial computing power. Our Beowulf system performs parallel calculations, dividing the calculation between the available computing nodes. Using codes such as AIMPRO, FEFF, DFTB and CASTEP it is possible to simulate microscopic and spectroscopic properties of nanoscale materials, aiding interpretation of experimental results and hopefully providing guidance and predictive ability for future experimental work.