electromagnetic radiation and x-rays
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
1
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
2
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
3
The Electromagnetic Waves
Light waves are self propagating waves that consist of both an electronic and magnetic component.
Insert electromagnetic wave image here
4
Formulas for Waves
Propagation Speedc = λfc is speed of propagation, (m/s)λ is wavelength, (m)f is frequency (/s, Hz, s-1)
PeriodT = 1/ff = 1/TWhere:T is the period (s)f is the frequency (Hz)
EnergyE = hfWhere:E is the energy of the photonh is Planck’s constantf is the frequency of the radiation
For light c is constant and equal to 2.998 x 108 m/s
5
The Electromagnetic Spectrum
Insert electromagnetic spectrum picture here
6
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.
7
CalculationsCalculate the frequency of a red laser pointer light with wavelength 655 nm.
8
CalculationsCalculate the wavelength and type of electromagnetic radiation you would expect to produce from a 3 GHz computer.
9
CalculationsA 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?
10
CalculationsCopper emits a kα X-ray of 8.04 keV. What would the wavelength be?
11
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
12
Discovery of X-rays
Wilhelm Röntgen
1895
http://en.wikipedia.org/wiki/X-ray
Insert Wilhelm Roentgen image here
Insert image of the first X-ray here
13
X-ray Tube
Insert X-ray tube image here
14
Two methods for generating X-rays
Bremsstrahlung / Braking Ionization / Characteristic
http://www.antonine-education.co.uk/Physics_A2/Options/Module_6/Topic_7/topic_7_x.htm
Insert imageInsert image
15
X-Ray Analysis Quantum numbers Electron Shells Allowed electron transitions
http://www4.nau.edu/microanalysis/Microprobe/Probe.html
Insert image
16
Quantum NumbersNumber 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
msSpin ±½ Electron spin
direction
j = l + ms Inner precession
l + ms
l ± ½
But j≠ -½
Total angular momentum
17
Principle Quantum Number, n
Shell Designation
Subshells
l
Number of states
Number of electrons
per subshell
per shell
1 K s 1 2 2
2 L s 1 2 8
p 3 6
3 M s 1 2 18
p 3 6
d 5 10
4 N s 1 2 32
p 3 6
d 5 10
f 7 14
18
Electron ShellsK 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 +½
j ½ ½ ½ 1½ ½ ½ 1½ 1½ 2½
19
Electron ShellsK
1s
LI
2s
LII
2p
-½
LIII
2p
+½
MI
3s
MII
3p
-½
MIII
3p
+½
MIV
3d
-½
MV
3d
+½
20
Electron Transitions1. The change in n must be ≥ 1 (Δn ≠ 0)
2. The change in l can only be ±1
3. The change in j can only be ±1 or 0
21
Calculation 1. The change in n must be ≥ 1 (Δn ≠ 0)
2. The change in l can only be ±1
3. The change in j can only be ±1 or 0
Quantum #
Δ
n
l
ml
ms
j
2p +½ to 1s
22
Example of Electron Transitions
Insert image
23
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