Chapter 03
Experimental Basis for
Quantum Theory
Version 110920, 110921
General Bibliography
1) Various wikipedia, as specified
2) Thornton-Rex, Modern Physics for Scientists & Eng, as indicated
Outline
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3.1 X-rays and Electrons
3.2 Electron Charge
3.3 Line Spectra
3.4 Quantization
3.5 Blackbody Radiation
3.6 Photoelectric Effect
3.7 X-Ray Production
3.8 Compton Effect
3.9 Pair Production & Annihilation
3.1 X-rays and Electrons
http://physics.kenyon.edu/EarlyApparatus/Static_Electricity/Geissler_Tubes/Geissler_Tubes.html
http://www.oneillselectronicmuseum.com/page9.html
http://www.beer-neon-signs.com/category/neon-business-signs
Geissler tubes
~1857
3.1 X-rays and Electrons
Discovered cathode rays
could be shifted by a magnet
http://www.magnet.fsu.edu/education/tutorials/museum/crookes_tube.html
Cathode rays (now called electrons)
Crookes Tubes
~1869
X-rays and Electrons
Hand mit Ringen (Hand with Rings): print of Wilhelm
Röntgen's first "medical" X-ray, of his wife's hand, taken
on 22 December 1895 and presented to Ludwig
Zehnder of the Physik Institut, University of Freiburg, on
1 January 1896[17][18]
X-rays and Electrons
1896 plaque published in "Nouvelle Iconographie de Salpetriere", a medical journal. In
the left a hand deformity, in the right same hand seen using radiography. The authors
designated the technique as Röntgen photography.
X-rays and Electrons
JJ Thomson
http://www.scifun.ed.ac.uk/pages/pp4ss/pp4ss-eoverm.html
http://ixnovi.people.wm.edu/Onebeautifulexperiment2008/emexperimentbywilliamsendor3.html
Charge of the Electron
3.3 Line Spectra
http://nothingnerdy.wikispaces.com/DIFFRACTION+GRATING
Pink Floyd:
Dark Side of the Moon
http://intro.chem.okstate.edu/1314f00/Lecture/Chapter7/Lec11300.html
k2
  364.56 2
k 4
nm
k = 3,4,5,6
http://www.chem1.com/acad/webtext/atoms/atpt-3.html
k2
  364.56 2
k 4
nm
4 1 1 

  2
 364.56  4 k 
1
1 1
 RH  2  2 

n k 
1
RH = 1.097e+7 m1
100 nm
vis
10000 nm
1000 nm
3.3 Line Spectra
3.5 Blackbody Radiation
http://www.mytightride.com/fof1fefl.html
3.5 Blackbody Radiation
http://en.wikibooks.org/wiki/Wikijunior:How_Things_Work/Light_Bulb
http://www.freefoto.com/preview/11-12-52/Electric-Light-Bulb
http://phet.colorado.edu/sims/blackbody-spectrum/blackbody-spectrum_en.html
3.5 Blackbody Radiation
Wein’s Law
maximum
2.898 103 m  K

T
Stefan-Boltzmann Law
Total Intensity eT 4
  5.6705  10 8
Watts
m2 K 4
e = 1 for perfect blackbody
3.5 Blackbody Radiation
Intensity 
UV
IR
2 c kT

4
3.5 Blackbody Radiation
Max Planck assumed some sort
of oscillators filled the cavity AND
energy difference between standing
wave modes = h f
Planck’s Radiation Law
2 c h
2

5
1
e
hc / kT
1
h = 6.626e-34 Js
3.6 Photoelectric Effect
http://en.wikipedia.org/wiki/Heinrich_Hertz
http://en.wikipedia.org/wiki/Induction_coil
Heinrich Hertz
Verified Maxwell
equations
prediction of
electromagnetic
waves
~1887
3.6 Photoelectric Effect
Photoelectric Effect Investigations
~1900
1. Higher intensity light did not change
the point at which current started to flow.
(i.e. energy of the electrons)
1’. More total incident energy did not increase
the energy of individual electrons.
2. Different colors of light changed the
starting point for current flow.
3.6 Photoelectric Effect
eVo  hf  
typically a few Volts at most
Implications: 1. EM waves have fixed energies (EM field is quantized)
2. Electrons are bound in a material by an amount determined
by the composition
3.7 X-Ray Production
(Bremsstralung + Characteristic X-Rays)
At fixed HV 35kV
Roentgen
characteristic
lines
min 
max Energy
E photon  hf
f  c
E photon 
hc

3.7 X-Ray Production
(Bremsstralung + Characteristic X-Rays)
Roentgen
3.7 X-Ray Production
(Bremsstralung + Characteristic X-Rays)
Do TV Sets Give Off X-Rays?
http://en.wikipedia.org/wiki/Cathode_ray_tube
X-rays may be produced when electrons,
accelerated by high voltage, strike an obstacle
while traveling in a vacuum, as in a TV containing
a cathode ray tube (CRT). Since many of the
components in television sets operate at
thousands of volts, there is the potential for x-ray
generation. These components may produce xrays capable of escaping from the television
receiver or CRT. This unintentional emission of xradiation can pose a potential hazard and must
be controlled.
http://www.fda.gov/Radiation-EmittingProducts/ResourcesforYouRadiationEmittingProducts/ucm252764.htm
http://www.orau.org/ptp/collection/xraytubescoolidge/xraytubescoolidge.htm
http://www.tradevv.com/chinasuppliers/eiffelgu_p_23e13/china-Portable-X-ray-flaw-detector-ceramic-tube.html
http://www.aerospacendt.com/Radiography.htm
Computed tomography (CT) scanning, also called computerized axial
tomography (CAT) scanning, is a medical imaging procedure that uses
x-rays to show cross-sectional images of the body.
A CT imaging system produces cross-sectional images or "slices" of
areas of the body, like the slices in a loaf of bread. These cross-sectional
images are used for a variety of diagnostic and therapeutic purposes.
How a CT system works:
http://www.strokecenter.org/patients/diagnosis/ct.htm
http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/MedicalImaging/MedicalX-Rays/ucm115317.htm
http://medicaltools.onsugar.com/Ct-Scan-Abdomen-Cancer-15819123
http://www.strokecenter.org/patients/diagnosis/ct.htm
http://info.shields.com/bid/43193/MRI-Images-torn-ACL-and-normal-ACL
Fluoroscopy is an imaging technique commonly used by physicians to
obtain real-time moving images of the internal structures of a patient through
the use of a fluoroscope. In its simplest form, a fluoroscope consists of an Xray source and fluorescent screen between which a patient is placed.
However, modern fluoroscopes couple the screen to an X-ray image
intensifier and CCD video camera allowing the images to be recorded and
played on a monitor.
http://en.wikipedia.org/wiki/Fluoroscopy
3.8 Compton Effect
Thomson Scattering
In classical description, scattering
occurs via dipole and scattered
photon of same frequency
(wavelength)
3.8 Compton Scattering
h
1  cos  
     
mc
'
h/mc =2.2426e-12 m
3.9 Pair Production & Positron
Annihilation
Pair Production
only if
hf  2mec2  2(0.511)  1.022 MeV
3.9 Pair Production & Positron
Annihilation
Positron Annihilation
Photons come out back-to-back
Photon energies are 0.511 MeV each
Positron emission
tomography (PET) is a
nuclear medicine imaging
technique that produces a
three-dimensional image or
picture of functional processes
in the body. The system
detects pairs of gamma rays
emitted indirectly by a
positron-emitting radionuclide
(tracer), which is introduced
into the body on a biologically
active molecule. Threedimensional images of tracer
concentration within the body
are then constructed by
computer analysis.
If the biologically active molecule chosen for PET is FDG, an analogue of
glucose, the concentrations of tracer imaged then give tissue metabolic
activity, in terms of regional glucose uptake.
http://en.wikipedia.org/wiki/PET_scanner
http://archives.drugabuse.gov/newsroom/03/NR9-08.html
Summary of Chapter 03
Strange things not known from classical physics
• New things
– Cathode rays  electrons
– X-rays
• Line spectra
– Gaseous discharges show lines rather than continous spectrum
• Blackbody radiation
– Rayleigh-Jeans classical formula clearly incorrect at explaining
spectrum
– Planck: oscillators with fixed energies
• Compton scattering
– Scattered photons have different wavelength in contast to
classical description
• Pair production & Positron annihilation
– Waves change into particles and vice versa