Transcript fn1_xrays

Electromagnetic
Radiation and X-Rays
"It's of no use whatsoever[...] this is just an
experiment that proves Maestro Maxwell was
right - we just have these mysterious
electromagnetic waves that we cannot see with
the naked eye. But they are there."
Heinrich Hertz
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Spectroscopy and X-Ray Analysis

Electromagnetic Radiation
 Electromagnetic
waves
 Calculations involving waves
 The electromagnetic spectrum
 Light and Optics
 Refraction and diffraction

X-Rays
 Discovery
of X-rays
 Generation of X-rays
 Quantum Numbers
 Electron Energy Transitions
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The Electromagnetic Waves
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Light waves are self propagating waves that consist
of both an electronic and magnetic component.
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Formulas for Waves
Propagation Speed
c = λf
Energy
E = hf
c is speed of propagation, (m/s) Where:
E is the energy of the photon
λ is wavelength, (m)
h is Planck’s constant
f is frequency (/s, Hz, s-1)
f is the frequency of the
radiation
Period
T = 1/f
f = 1/T
For light c is constant and
equal to 2.998 x 108 m/s
Where:
T is the period (s)
f is the frequency (Hz)
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The Electromagnetic Spectrum
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EM Radiation Activity

You will each be assigned one of the following
types of electromagnetic radiation. Look it up.
Report the following information for it:
 Wavelength
 How
it is generated
 What it are some common uses

Gamma rays, X-rays, Ultraviolet radiation, Light,
Infra-red radiation, Microwaves, Radio waves
(FM, AM, ELF), Gravity waves.
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Calculations
Calculate the frequency of a red laser pointer light with wavelength 655
nm.
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Calculations
Calculate the wavelength and type of electromagnetic radiation you
would expect to produce from a 3 GHz computer.
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Calculations
A common unit in spectroscopy is the “wave number” which is usually
defined as the number of waves per cm.
How many wave cycles per cm (wave numbers) would you expect to
find in radiation produced from a microwave oven operating at a
frequency of 2450 MHz?
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Calculations
Copper emits a kα X-ray of 8.04 keV. What would the wavelength be?
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Light and Optics

Electromagnetic radiation
 What
we see as light is part of the electromagnetic
spectrum.
 Photon: a unit of electromagnetic energy (light).
Photons have no electric charge, they have zero “rest
mass” but they do have momentum and energy.

http://hyperphysics.phy-astr.gsu.edu/hbase/emwav.html#c1
http://en.wikipedia.org/wiki/Electromagnetic_radiation
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Discovery of X-rays
1895
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Roentgen image here
Insert image of the
first X-ray here
Wilhelm Röntgen
http://en.wikipedia.org/wiki/X-ray
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X-ray Tube
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Two methods for generating X-rays
Bremsstrahlung / Braking
Ionization / Characteristic
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http://www.antonine-education.co.uk/Physics_A2/Options/Module_6/Topic_7/topic_7_x.htm14
X-Ray Analysis



Quantum numbers
Electron Shells
Allowed electron transitions
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http://www4.nau.edu/microanalysis/Microprobe/Probe.html
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Quantum Numbers
Number
Name
Permitted Values
Defines
n
Principal
(1, 2, 3, …)
Electron shell
(1=K, 2=L, 3=M
…)
l
Azimuthal
0 to n-1
Electron cloud
shape
ml
Magnetic
-l to +l
Electron shell
orientation in a
magnetic field
ms
Spin
±½
Electron spin
direction
j = l + ms
Inner precession
l + ms
l±½
But j≠ -½
Total angular
momentum
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Principle
Shell
Quantum Designation
Number, n
Subshells Number
of states
l
Number of electrons
per
subshell
per shell
1
2
K
L
s
s
p
1
1
3
2
2
6
2
8
3
M
N
1
3
5
1
2
6
10
2
18
4
s
p
d
s
p
3
6
d
5
10
f
7
14
32
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Electron Shells
K
LI
LII
LIII
MI
MII
MIII MIV MV
n
1
2
2
2
3
3
3
3
3
l
0
0
1
1
0
1
1
2
2
s
+½ +½ -½
+½ +½ -½
+½ -½
j
½
1½ ½
1½ 1½ 2½
½
½
½
+½
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Electron Shells
K
1s
LI
2s
LII
2p
-½
LIII MI
2p 3s
+½
MII
3p
-½
MIII MIV MV
3p 3d 3d
+½ -½ +½
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Electron Transitions
1.
2.
3.
The change in n must be ≥ 1 (Δn ≠ 0)
The change in l can only be ±1
The change in j can only be ±1 or 0
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Calculation
1.
2.
3.
The change in n must be ≥ 1 (Δn ≠ 0)
The change in l can only be ±1
The change in j can only be ±1 or 0
2p +½ to 1s
Quantum
#
n
l
ml
ms
j
Δ
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Example of Electron Transitions
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Spectroscopy and X-Ray Analysis

Electromagnetic Radiation
 Electromagnetic
waves
 Calculations involving waves
 The electromagnetic spectrum
 Light and Optics
 Refraction and diffraction

X-Rays
 Discovery
of X-rays
 Generation of X-rays
 Quantum Numbers
 Electron Energy Transitions
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