Chapter 03Experimental Basis for

Quantum Theory

General Bibliography1) Various wikipedia, as specified

2) Thornton-Rex, Modern Physics for Scientists & Eng, as indicated

Version 110920, 110921

Outline

• 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

Geissler tubes~1857

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

3.1 X-rays and Electrons

Crookes Tubes~1869

http://www.magnet.fsu.edu/education/tutorials/museum/crookes_tube.html

Cathode rays (now called electrons)

Discovered cathode rays could be shifted by a magnet

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 ElectronsJJ 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

Pink Floyd: Dark Side of the Moon

http://intro.chem.okstate.edu/1314f00/Lecture/Chapter7/Lec11300.html

http://nothingnerdy.wikispaces.com/DIFFRACTION+GRATING

http://www.chem1.com/acad/webtext/atoms/atpt-3.html

nmk

k

456.364

2

2

k = 3,4,5,6

2

1

4

1

56.364

41

k

22

111

knRH

nmk

k

456.364

2

2

RH = 1.097e+7 m

3.3 Line Spectra

Lym

an n

=1

Balm

er n

=2

Pasc

hen

n=3

Bra

cket

t n=4

Pfund

n=5

100

nm

1000

nm

1000

0 nm

vis

3.5 Blackbody Radiation

http://www.mytightride.com/fof1fefl.html

3.5 Blackbody Radiation

http://phet.colorado.edu/sims/blackbody-spectrum/blackbody-spectrum_en.html

http://www.freefoto.com/preview/11-12-52/Electric-Light-Bulb

http://en.wikibooks.org/wiki/Wikijunior:How_Things_Work/Light_Bulb

3.5 Blackbody RadiationWein’s Law

Stefan-Boltzmann Law

428106705.5

Km

Watts

= 1 for perfect blackbody

T

Kmimum

3

max

10898.2

4TIntensityTotal

3.5 Blackbody Radiation

4

2

kTc

Intensity

IRUV

3.5 Blackbody Radiation

1

12/5

2

kThce

hc

Max Planck assumed some sort of oscillators filled the cavity AND energy difference between standing wave modes = h f

Planck’s Radiation Law

h = 6.626e-34 Js

3.6 Photoelectric Effect

Heinrich Hertz

http://en.wikipedia.org/wiki/Heinrich_Hertz

Verified Maxwell equations prediction of electromagnetic waves

http://en.wikipedia.org/wiki/Induction_coil

~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

hfeVoWork function

Energy of an individual photon

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

typically a few Volts at most

3.7 X-Ray Production(Bremsstralung + Characteristic X-Rays)

Roentgen

min max Energy

characteristic lines

hc

E

cf

hfE

photon

photon

At fixed HV 35kV

3.7 X-Ray Production(Bremsstralung + Characteristic X-Rays)

Roentgen

3.7 X-Ray Production(Bremsstralung + Characteristic X-Rays)

http://en.wikipedia.org/wiki/Cathode_ray_tube

Do TV Sets Give Off X-Rays?

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 x-rays capable of escaping from the television receiver or CRT. This unintentional emission of x-radiation 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.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/MedicalImaging/MedicalX-Rays/ucm115317.htm

http://www.strokecenter.org/patients/diagnosis/ct.htm

http://www.strokecenter.org/patients/diagnosis/ct.htmhttp://medicaltools.onsugar.com/Ct-Scan-Abdomen-Cancer-15819123

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 X-ray 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 EffectThomson Scattering

In classical description, scattering occurs via dipole and scattered photon of same frequency (wavelength)

3.8 Compton Scattering

cos1' mc

h

h/mc =2.2426e-12 m

3.9 Pair Production & Positron Annihilation

MeVcmhfifonly e 022.1)511.0(22 2

Pair Production

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. Three-dimensional images of tracer concentration within the body are then constructed by computer analysis.

http://en.wikipedia.org/wiki/PET_scanner

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://archives.drugabuse.gov/newsroom/03/NR9-08.html

Summary of Chapter 03Strange 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