www.reading.ac.uk/EMLab

Transmission Electron Microscopy

Peter Harris

EM Workshops 2017

Transmission electron microscopy

► What is transmission electron microscopy?

► TEM in biological science

► EMLab’s TEMs

► TEM in physical science

► Capabilities of our new TEM

EM Workshops 2017

SEM & TEM

Scanning electron microscope

Electron gun

Specimen

Electron gun

Condenser lens

Objective lens

Specimen

Projector lens

Fluorescent screen

Electron gun

Digital camera

Condenser lens

Objective lens

Specimen

Projector lens

Fluorescent screen

Electron gun

Digital camera

Transmission electron microscope

EM Workshops 2017

Transmission electron microscopy

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.

Electron gun

Current passed through LaB6 crystal causes electrons to be emitted. Anode accelerates electrons to 80 kV – 200kV.

EM Workshops 2017

Transmission electron microscopy

Specimens for TEM

3 mm TEM grid

Carbon films

EM Workshops 2017

Absorption contrast:

Heavy atoms absorb more

electrons than light atoms.

Contrast in the TEM - 1

Biological and “soft matter”

Scattering contrast:

Some electrons blocked by

objective aperture.

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Positive staining

Electron-dense heavy metal salt selectively stains certain features within the sample.

Block copolymer containing polystyrene and polymethylmethacrylate stained with ruthenium tetroxide.

EM Workshops 2017

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.

Commonly used stains: uranyl acetate, uranyl formate, sodium/potassium phosphotungstate, ammonium molybdate.

Adenovirus negatively stained with uranyl acetate

EM Workshops 2017

Biological TEM - negative staining

Peptide fibrils, stained with methylamine tungstate (1%) on formvar/carbon grids.

Marta Krysmann, School of Chemistry

EM Workshops 2017

Biological TEM – preparing specimens from tissue

Microtome

Fix dehydrate set in resin section deposit on grids stain

EM Workshops 2017

Biological TEM – thin section

Kidney

EM Workshops 2017

Biological TEM – thin section

Chloroplast of basil leaf. Dr Carol Wagstaff, Kala Radha (Food Biosci) & Matthew Spink (EMLab).

Biological specimen preparation for TEM: 28 November

EM Workshops 2017

Easy!

TEM – specimen prep of inorganic powders

EM Workshops 2017

Electron diffraction

Diffraction pattern (crystalline C60)

EM Workshops 2017

Diffraction contrast

Contrast in the TEM - 2

EM Workshops 2017

Transmission electron microscopy

TEM in physical science – bright field imaging

Dislocations in stainless steel foil

Platinum/alumina catalyst

EM Workshops 2017

Phase contrast: lattice imaging

Contrast in the TEM - 3

EM Workshops 2017

Multiple electron scattering

Electrons passing through a crystal are multiply scattered

EM Workshops 2017

Image simulations

Example of image simulation: amphibole crystal

EM Workshops 2017

EM Lab’s TEMs

JEOL 2010 High resolution TEMJEOL 2100Plus TEM/STEM

(installed Feb. 2017)

EM Workshops 2017

Electron Microscopy Laboratory

Our new transmission electron microscope

JEOL 2100Plus

Capabilities:

Cryo imaging

Tomography

EM Workshops 2017

Cryo-TEM

● Samples suspended in amorphous ice

● No dehydration, fixing or staining: shows samples in their native environment

● Usually carried out using automatic plunge-freezer

FEI Vitrobot

EM Workshops 2017

Cryo-TEM

EM Workshops 2017

Cryo -TEM

Cryo-TEM of influenza virions

EM Workshops 2017

Nobel Prize for Chemistry 2017

EM Workshops 2017

Tomography – bringing the 3rd dimensionto TEM

EM Workshops 2017

Electron tomography

Tilt series of carbon

nanostructures

EM Workshops 2017

TEM at EMLab

Carbon nanostructures

EM Workshops 2017

TEM at EMLab

Nanoporous Pt particles -applications in catalysis.

Samina Akbar& Joanne Elliott,Department of Chemistry

EM Workshops 2017

TEM at EMLab

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

EM Workshops 2017

Pseudomonas fluorescens bacteria, stained with UA. Othman Mohammed/Sheila MacIntyre, SBS.

EM Workshops 2017

TEM at EMLab

Chicken cells infected with coronaviruses.

Hasan Alrashedi, SBS.

EM Workshops 2017

Becoming an EMLab user

Sherrie Foo

EM Workshops 2017

Booking system

EM Workshops 2017

Remaining workshops

Date Topic

7 November 2017Environmental & Cryo

SEM

14 November 2017Biological specimen

preparation for SEM

21 November 2017X-ray Analysis and

Elemental Mapping

28 November 2017Biological specimen

preparation for TEM

EM Workshops 2017

► Questions?

Transmission electron microscopy

► Demo