Transmission Electron Microscopy Peter Harris

Transmission electron microscopy ► What is transmission electron microscopy? ► TEM in biological science ► TEM in physical science ► CfAM’s TEMs ► Recent developments in TEM

SEM & TEM Scanning electron microscope Specimen Condenser lens Objective lens Specimen Projector lens Fluorescent screen Electron gun Digital camera Electron gun Electron gun Electron gun Condenser lens Objective lens Specimen Projector lens Fluorescent screen Digital camera Scanning electron microscope Transmission electron microscope

Transmission electron microscopy Electron gun Current passed through LaB6 crystal causes electrons to be emitted. Anode accelerates electrons to 80 kV – 200kV. Electromagnetic lenses A current through the coils creates a magnetic field, symbolized by red lines in the diagram on the left. Electrons close to the centre are less strongly deflected than those passing through the lens far from the axis.

Transmission electron microscopy Specimens for TEM 3 mm TEM grid Carbon films

Contrast in the TEM - 1 Biological and “soft matter” Absorption contrast: Heavy atoms absorb more electrons than light atoms. Scattering contrast: Some electrons blocked by objective aperture.

Positive staining Electron-dense heavy metal salt selectively stains certain features within the sample. Block copolymer containing polystyrene and polymethylmethacrylate stained with ruthenium tetroxide.

Biological TEM - negative staining Surrounding biomolecules with thin amorphous layer of heavy metal salt. Reveals structure, and reduces structural flattening that occurs in the absence of stain. Adenovirus negatively stained with uranyl acetate Commonly used stains: uranyl acetate, uranyl formate, sodium/potassium phosphotungstate, ammonium molybdate.

Biological TEM - negative staining Peptide fibrils, stained with methylamine tungstate (1%) on formvar/carbon grids. Marta Krysmann, School of Chemistry

Biological TEM – preparing specimens from tissue Fix  dehydrate  set in resin  section  deposit on grids  stain Microtome

Biological TEM – thin section Kidney

The transmission electron microscope is not just a microscope! Diffraction pattern (crystalline C60) Energy dispersive X-ray spectrum X-ray analysis workshop: November 27 

Contrast in the TEM - 2 Diffraction contrast

Transmission electron microscopy TEM in physical science – bright field imaging Platinum/alumina catalyst Dislocations in stainless steel foil

Contrast in the TEM - 3 Phase contrast: lattice imaging

Multiple electron scattering Electrons passing through a crystal are multiply scattered

Image simulations Example of image simulation: amphibole crystal

EM Lab’s TEMs FEI/Philips CM20 Analytical TEM JEOL 2010 High resolution TEM

New developments in TEM - 1 Ultra-high resolution TEM, with aberration correction, Tsukuba, Japan.

New developments in TEM - 2 Tomography – bringing the 3rd dimension to TEM

TEM at CfAM Carbon nanostructures

TEM at CfAM Nanoporous Pt particles - applications in catalysis. Samina Akbar& Joanne Elliott, Department of Chemistry

TEM at CfAM Micro-phase separated polymer particle, 120nm diameter. Hamley group.

Becoming an EMLab user Sherrie Foo

Remaining workshops Environmental & Cryo SEM 20 November 2013 Date Topic 20 November 2013 Environmental & Cryo SEM 27 November 2013 X-ray Analysis and Elemental Mapping

Transmission electron microscopy ► Questions? ► Demo