Amber…Greek name for amber was ἤλεκτρον
(elektron), “formed by the sun”
Around 600bc, the Greek philosopher and scientist
Thales of Miletus discovered that rubbing amber
with a wool cloth would cause it to mysteriously
attract paper, grass or feathers.
Electricity!
We learned shocking
power (and something
about forces of nature)
from lightning…and
fish!
Electric catfish (Malapterurus electricus) 350V
Electricity!
Electric “eel” (Electrophorus electricus) 600V
We learned shocking
power (and something
about forces of nature)
from lightning…and
fish!
Electric rays (~60 species) 40-50V
Elektron, the Greek word for amber…
William Gilbert (1600) is the first to recognize
the difference between the magnetic
attraction of magnetite, and the static charge
attraction built up on the surface of amber
after it is rubbed…
“electricus”
Ben Franklin
1752, lightning =static
charge
1755, charge exists on
the exterior of a
charged object…the
interior is unaffected
(the cage effect)
George Johnstone Stoney
G. Johnstone Stoney in Aug. 1874, and again in Feb. 1881.
"And, finally, Nature presents us, in the phenomenon of electrolysis, with a
single definite quantity of electricity which is independent of the particular
bodies acted on. To make this clear I shall express `Faraday's Law' in the
following terms, which, as I shall show, will give it precision, viz.:-- For each
chemical bond which is ruptured within an electrolyte a certain quantity of
electricity traverses the electrolyte which is the same in all cases. This definite
quantity of electricity I shall call Er. If we make this our unit quantity of
electricity, we shall probably have made a very important step in our study of
molecular phenomena."
1891
“In this paper an estimate was made of the actual amount of this most remarkable
fundamental unit of electricity, for which I have since ventured to suggest the name electron.
According to this determination the electron = a twentiethot (that is 10¯20) of the quantity of
electricity which was at that time called the ampere…”
Development of quantum theory
John Dalton (1766-1844)
-1808 Every element consists of indivisible particles called atoms
James Clerk Maxwell (1831-1879)
-1865 Maxwell’s field equations –
The birth of field theory (from Faraday)
The electromagnetic theory of lightLight propagates as waves
Michael Faraday
Johann Balmer (1825-1898)
(1831), the
-1885 Discovers numerological relationship between frequency electromagnetic field
and prominent spectral lines of hydrogen:
n = integer
ν = frequency
c = speed of light
R = Rydberg
constant
William Thomson, the first Baron Kelvin
Wilhelm Conrad Roentgen (1845-1923)
-1895 Demonstrates X-rays in experiments with
passing electric current through lowpressure gas
First Nobel Prize in Physics!
J.J. Thompson (1856-1940)
-1897 Identifies “cathode rays” as negative
particles = electrons
“The more important fundamental laws and facts of physical science
have all been discovered, and these are now so firmly established
that the possibility of their ever being supplanted in consequence of
new discoveries is exceedingly remote . . . Our future discoveries
must be looked for in the sixth place of decimals.”
Albert A. Michelson, 1894
“There is nothing new to be discovered in physics now. All that
remains is more and more precise measurement.”
William Thomson (Lord Kelvin), 1900
John William Strutt, 3rd Baron Rayleigh – Rayleigh scattering, Rayleigh waves, the theory of
sound (his son was Robert John Strutt, 4th Baron Rayleigh – electrons
and gases, radiation)
Lord Rayliegh (1842-1919) and
James Jeans (1877-1946)
-1900 Calculation of black body radiation
“Ultraviolet catastrophe”
Max Plank (1858-1947)
-1901 Introduces the quantum concept Absorption and emission of radiant
energy in discrete packets
“An indispensable hypothesis, even though still far from being a guarantee of success, is
however the pursuit of a specific aim, whose lighted beacon, even by initial failures, is
not betrayed.
For many years, such an aim for me was to find the solution to the problem of the
distribution of energy in the normal spectrum of radiating heat.”
– Nobel Lecture of Max Plank (1920)
E = hν
h = 6.6262 x 10-34 kg m2 / sec
Albert Einstein (1879-1955)
-1905 Photoelectric effect and the
photon concept…
Special relativity too!
Ernest Rutherford (1871-1937)
-1911
An atom consists of a
positively charged nucleus and
negatively charged electrons orbiting
the nucleus at constant speed
Niels Bohr (1885-1962)
-1913 Quantum model of hydrogen
(early quantum theory)
Predicts the Rydberg constant and the line
spectra for gaseous hydrogen
Bohr’s Three Postulates:
1) There are certain orbits in which the electron is stable and does not radiate
The energy of an electron in an orbit can be
calculated - that energy is directly proportional to the
distance from the nucleus
Bohr simply forbids electrons from occupying just any orbit around the
nucleus such that they can’t lose energy and spiral in…
2) When an electron falls from an outer orbit to an inner orbit, it loses energy
…expressed as a quantum of electromagnetic radiation
3) A relationship exists between the mass, velocity and distance from the
nucleus of an electron and Planck’s quantum constant…
From these principles, Bohr realized he could calculate the energy
corresponding to an orbit:
m = mass of electron
e = charge of electron
ħ = h / 2π
If an electron jumps from orbit n=2 to orbit n, the energy loss is:
energy is radiated, and expressing Plank’s relationship in terms of angular
frequency (ω), rather than frequency (ν):
Bohr theoretically has expressed Balmer’s formula and could
calculate the Rydberg constant knowing m, e, c, and ħ
Modern quantum theory:
Louis de Broglie (1892-1987)
-1924
wave theory of matter
ultimately led to the development of
wave mechanics
λ particle wavelength
h Planck’s constant
p particle momentum
m rest mass
ν particle velocity
Wolfgang Pauli (1900-1958)
-1925
the exclusion principle
No two electrons can be in the same place at
the same time
Electrons in an atom can be described by four
quantum numbers
No two electrons in an atom can have the
same set of quantum numbers
Predicted the neutrino!
Werner Heisenberg (1901-1976)
-1925 matrix mechanics
Observables are the sole source of change
-State vector does not change with time
Erwin Schrödinger (1887-1961)
-1926 wave mechanics
states are the sole source of change
Max Born (1882-1970)
-1926 Waves are probability waves
Paul Dirac (1902-1984)
-1925-28
Quantum field theory
Resolved particle-wave duality
Predicted antimatter
The relativistic quantum mechanical wave function (a
relativistic generalization of the Schrodinger equation):
Hans Bethe (1906-2005)
-1930 Evaluates passage of charged particles
through matter
From first Born approximation:
Bethe’s ionization equation – the probability of ionization of
a given shell (nl)
Describes energy loss of charged particle with distance …
Bethe equation:
Development of concepts - SEM
Ernst Abbe (1840-1905)
-1878
Geometric optics and the
resolving power of a microscope
What is resolution?
All lens images are diffraction patterns
(circular slit diffraction)
An image point will be a disk, surrounded by diffraction rings
representing diffraction maxima and minima
Rayleigh Criterion: Central maximum produced by one object point must exceed the first
diffraction minimum of the other object point…
fully resolved
just resolved
unresolved
At small angles…
A
O’
d
i
I
O
θ
B
I’
Extreme rays from O’ to I differ by
1.22λ, so …
O’
s
i
Total path difference is then…
and
O
The Abbe
equation
Here, n is the refractive index
1)
2)
Visible light λ = 560 nm, for aperture
angle of 0.9, and n = 1…
Electrons (remember de Broglie and the wave theory of matter)
λ = 0.0054 nm…
True resolution depends on
1) Beam brightness
2) Lens aberrations
3) Scattering in specimen
Electron
voltage (kV)
Relativistic
Mass (EU)
Wavelength
(nm)
Abbe resolution
(Å)
5
1.0097
1.726e-2
10.563
10
1.0195
1.214e-2
7.433
20
1.0391
8.507e-3
5.206
50
1.0978
5.235e-3
3.204
200
1.3913
2.325e-3
1.423
400
1.7827
1.452e-3
0.889
Mass of an electron = 9.1091 X 10-31 kg
Speed of light = 299,790,000 meters/second
Energy of an electron = 1.602 X 10-19 Newton meters/second
Planck's Constant = 6.6256 X 10-34
Accelerating voltage physics calculator, University of Oklahoma electron
microscopy laboratory
Louis de Broglie and the wave theory of matter
allow the introduction of the basic concept of
electron microscopy, but before that…
-1913
Henry Moseley (1887-1915)
Following Bohr’s work, he demonstrates that the
wavelengths of emitted X-rays correlates with
atomic number
Moseley’s Law:
f= frequency, Z = atomic #
k1 and k2 are constants
-1914
Max von Laue (1879-1960) shows that a beam of X-rays
passing through a crystal produces a diffraction pattern.
-1914
Karl Siegbahn (1886-1978) Discovered M-series of
wavelengths in X-ray emission spectra, and developed methodology and
instrumentation for detailed X-ray spectroscopy.
-1915
William Bragg (1864-1942) and his son, W. Lawrence Bragg
(1890-1971) pioneer the analysis of crystal structure using X-ray
diffraction.
d
SEM and EPMA development
1926 – Hans Busch establishes geometrical electron optics
theoretically
1927 – Hugo Stintzing develops the cathode-ray scanning
microphotometer, and essentially develops the concept of the
scanning electron microscope
1928 – Ernst Ruska experimentally demonstrates
electromagnetic focusing.
1931 – Max Knoll and Ernst Ruska build
the first transmission electron microscope
(Berlin) (receives Nobel Prize…1986)
“conventional” TEM, not scanning
1931 – Johann and Cauchois develop sem-focusing spectrometers by
bending multilayer structures.
1932 – Johansson develops the focusing spectrometer by bending a
crystal to twice the radius if the focusing circle, then grinding to achieve
full focus.
1938 - Manfred von Ardenne
Credited with developing the first scanning
electron microscope
The first commercial electron microscope is
introduced by Siemens
1942 – Vladimir Zworykin, James Hillier, and
R.L.Snyder develop the first thick specimen
SEM at RCA labs
Vladimir Zworykin
TV!
1943 – James Hillier develops the concept for electron
probe microanalysis – the use of a focused electrons
impinging on a specimen and their utility in chemical
characterization.
1949-1951 Raimond Castaing develops
the concept for electron-probe, X-ray
microanalysis (using characteristic X-rays
for chemical analysis), and builds the first
electron microprobe in Paris
This becomes the basis for the first
commercial instrument, introduced by
Cameca in 1956
1965 – First commercial SEM is offered by Cambridge
Instruments
(The first commercial TEM had been introduced by
Philips Electron Optics in 1949)
Many commercial SEMs today:
JEOL (Japan Electron Optics Lab)
Hitachi
Carl Zeiss
Cambridge Instruments + Wild Leitz = Leica (1990)
Carl Zeiss + Leica = LEO (1995)
LEO integrated into Carl Zeiss (2004)
Carl Zeiss acquires ALIS (2006)
ALIS
FEI
FEI and Philips Electron Optics merge 1997
FEI acquires Micrion 1999
Tescan
Camscan
Topcon / ISI
1960s brought expansion of electron microprobe technology and
commercial availability:
Cameca
JEOL
Cambridge Instruments
Advanced Metals Research
Applied Research Laboratories
Elion Instruments
Materials Analysis Company
Hitachi
Only Cameca and JEOL offer dedicated electron microprobes today
SEM technology today:
Ultra-high resolution
(now to 0.4-0.5nm, Hitachi S-5500)
Cold field emission
Schottky emission
Variable pressure
SEM technology today:
Extreme high resolution
Sub nm image resolution for full voltage range
Analytical current capability
(FEI Magellan)
Energy filtered Schottky emission
STEM / SEM
Ti barrier
Sidewall spacer
Poly
Si
W
contact
Al line
Electron BackScatter Diffraction
(EBSD)
Quartz orientation map
Combined FIB / SEM (dual beam)
The synergistic approach:
EPMA+FIB+APT
Helium ion microscope – ultra high resolution microscopy
Achieved 0.24nm image resolution