Overview Notebook¶

part of

MSE672: Introduction to Transmission Electron Microscopy

Spring 2025
by Gerd Duscher

Microscopy Facilities
Institute of Advanced Materials & Manufacturing
Materials Science & Engineering
The University of Tennessee, Knoxville

Import packages for figures and¶

First we load the code to make figures from pyTEMlib

Check Installed Packages¶

import sys
import importlib.metadata
def test_package(package_name):
    """Test if package exists and returns version or -1"""
    try:
        version = importlib.metadata.version(package_name)
    except importlib.metadata.PackageNotFoundError:
        version = '-1'
    return version

if test_package('pyTEMlib') < '0.2025.1.0':
    print('installing pyTEMlib')
    !{sys.executable} -m pip install  --upgrade pyTEMlib -q
print('done')

done

Load the plotting and figure packages¶

%matplotlib widget

import matplotlib.pylab as plt
import numpy as np
import sys
if 'google.colab' in sys.modules:
    from google.colab import output
    output.enable_custom_widget_manager()

import pyTEMlib.animation as animate

You don't have igor2 installed.     If you wish to open igor files, you will need to install it     (pip install igor2) before attempting.
You don't have gwyfile installed.     If you wish to open .gwy files, you will need to      install it (pip install gwyfile) before attempting.
Symmetry functions of spglib enabled
Using kinematic_scattering library version {_version_ }  by G.Duscher

History¶


1925	Louis de Broglie	electron has a wavelike character with a wavelength less than light
1927	Davisson and Germer	classic electron diffraction experiments
	Thompson and Reed
1932	Knoll and Ruska	first electron lenses and first image (Noble Price 1986)
1936	Vickers	first commercial electron TEM
1939	Siemens and Halske	first usable and profitable TEM
1949	Heidenreich	first transparent metal foil (first materials science result)
2000	Krivanek	(STEM) first prototypes for spherical aberration
	Rose/Heider	(TEM) objective-lens correctors
2007	Krivanek	(STEM) first prototypes for fifth order
	Rose/Heider	(TEM) aberration objective-lens correctors

Available TEMs¶

TEMs are now available from many sources ( for example: FEI, Hitachi, JEOL, Nion).

TEMs available in the UTK/ORNL area.¶

Zeiss Libra200 MC at UTK
ThermoFischer Spectra300 at UTK 5th order corrected
JEOL 2100+ at Tennessee Ion Beam Materials Laboratory/UTK
Nion UltraSTEM 100 at ORNL/CNMS, 5th order corrected
JEOL 2100 at ORNL 3rd order corrected
FEI Titan at ORNL/CNMS, 3rd order corrected
JEOL ARM at ORNL/CNMS, 5th order corrected
Nion UltraSTEM 200 at ORNL, 5th order corrected
NionMACSTEM 100 at ORNL, 5th order corrected
FEI Talos F200X S/TEM at ORNL,
Hitachi 300 at ORNL

The dedicated STEMs are all equipped with a spherical aberration corrector by Nion. There are also four CEOS (Haider and Rose) aberration corrected TEMs (ThermoFisher and JEOL).

Electron Meets Matter¶

To gather information about a sample the electron has to interact with this sample, otherwise it would be invisible. There is a whole zoo of interactions. The primary and most important interaction for TEM imaging is (elastic and inelastic) scattering. All the other processes are secondary (for example: X-ray emission).

Diffraction and Imaging¶

No interaction

Most electrons do not interact with a thin specimen at all.

Interaction without energy transfer

Elastic scattering is the basis for diffraction and imaging.

Interaction with energy transfer

Inelastic scattering causes a diffuse background in images and diffraction pattern, but can be used for analytical TEM.

Modes of a TEM¶

Some techniques:


SAED	selected area electron diffraction
CBED	convergent beam electron diffraction
Kikuchi	Kikuchi diffraction
Fresnel	Fresnel diffraction
CTEM	conventional transmission electron microscopy
BF	bright field imaging
DF	dark field imaging
HRTEM	high resolution (phase contrast)
SE	secondary electron imaging
BE	backscatter electron imaging
Lorentz	Lorentz microscopy
HAADF	high angle annular dark field imaging (Z-contrast)

Modes of a TEM/STEM¶

	illumination	objective	projective	I projective II
TEM	TEM	Mag	Image	ESI
Nanoprobe	Spot	Mag	Image	ESI
LowMag	TEM	LowMag	Image	ESI
Microprobe	Spot	LowMag	Image	ESI
SAED	TEM	Mag	Diffr	ESI
Low angle diffraction	TEM	LowMag	Diffr	ESI
CBED	Spot	Mag	Diffr	ESI
LACBED	Spot	LowMag	Diffr	ESI
Spectroscopy	TEM	Mag	Image	EELS
Spectroscopy	Spot	Mag	Diffr	EELS
STEM	Spot	Mag	Diffr	ESI
STEM-LM	Spot	LowMag	Diffr	ESI
STEM-SI	Spot	Mag	Diffr	EELS

The main ingredients in an TEM method are how is the sample illuminated (condenser) and how are the electrons sorted and selected (projector and spectrometer).

Diffraction and Imaging¶

Even though we are dealing with relativistic and quantum mechanical principles the geometric ray diagrams are essential for an understanding of how to set up a TEM mode.

# ---INPUT------ #
focal_length = 1.4
# -------------- #

animate.geometric_ray_diagram(focal_length, magnification=True)

Basics of Diffraction¶

Diffraction is the direct result of the interaction (without energy transfer) of electrons and matter.
Kinematic diffraction theory describes only the Bragg angles (the position) but not the intensity in a real electron diffraction pattern.
Dynamic theory is responsible for the intensity distribution in an electron diffraction pattern

Diffraction and Imaging¶

To form an image from a diffraction pattern only a Fourier transformation of parts of the diffraction pattern is needed.
Any image in a TEM can be described as Fourier filtering, because we select beams. The knowledge of which and how many diffracted beams contribute to the image formation is crucial for interpretation.
Because the intensity of selected diffracted beams is necessary to calculate image intensities, dynamic theory is necessary.
Understanding diffraction theory of electrons is the core of the analysis of TEM data.

Electron Energy-Loss Spectroscopy¶

No Energy Transfer

The zero-loss peak is caused by electrons of the acceleration energy which apparently did not loose any energy.

Little Energy Transfer: 1-70 eV

The valence-loss region shows intraband, interband, and plasmon transitions.

High Energy Transfer: above 70eV

The core-loss region contains excitation from the atom core levels into the conduction band appear as saw tooth like edges.

Secondary Processes¶

After excitation through the incident electrons, the atoms will fall back to their ground state and emit the gained energies as photons (in the light and X-ray region) or (Auger-) electrons. These secondary processes are also used for analytical analysis such as:

Energy Dispersive X-Ray Spectroscopy (EDS)
Auger-Spectroscopy
Cathodoluminescence

Drawbacks of Transmission Electron Microscopy¶

Sample preparation is tedious and can induce artifacts.
Sampling: Only a small area is getting investigated.
Electron beam damage
Sample contamination
Image/data interpretation is not easy:
A micrograph is a projection only, and high resolution images must be simulated.
The instruments are under vacuum and are generally fragile, which results in long experimental times.

Summary¶

The TEM enables many powerful techniques.
The TEM is only useful to solve problems needing spatially resolved information
The TEM is most powerful with complementary (less spatially resolved) techniques

Outlook¶

The interpretation of selective area diffraction.
Next: Geometric Ray Optics.

Read your Assignment¶

Carter and Williams: Chapter 6

Back Course Organization
Next: Electron_Optics
Chapter 1: Introduction
List of Content: Front

Overview Notebook

Overview Notebook¶

Import packages for figures and¶

Check Installed Packages¶

Load the plotting and figure packages¶

History¶

Available TEMs¶

TEMs available in the UTK/ORNL area.¶

Electron Meets Matter¶

Diffraction and Imaging¶

Modes of a TEM¶

Modes of a TEM/STEM¶

Diffraction and Imaging¶

Basics of Diffraction¶

Diffraction and Imaging¶

Electron Energy-Loss Spectroscopy¶

Secondary Processes¶

Drawbacks of Transmission Electron Microscopy¶

Summary¶

Outlook¶

Read your Assignment¶

Navigation¶