Transcript History of QM, part 2

Nature of Light
Young
Wave
Einstein
Particle (photon)
Wave-Particle Duality
(What does this mean?)
Rutherford’s Gold Foil Experiment
Ernest Rutherford (1871 – 1937)
One day Geiger came to and said, “Don’t you think that young Marsden,
whom I am training in radioactive methods, ought to begin a small
research?” Now I had thought that too, so I said, “Why not let him
see if any alpha particles can be scattered through a large angle?” I may
tell you in confidence that I did not believe that there would be, since
we knew the alpha particle was a very fast massive particle, with a great
deal of energy, and you could show that if the scattering was due to the
accumulated effect of a number of small scatterings the chance of an alpha
particle being scattered backward was very small.
Then I remember two or three days later Geiger coming to me in
great excitement and saying, “We have been able to get some of
the alpha particles coming backwards…” It was quite the most
incredible event that has ever happened to me in my life. It was
almost as incredible as if you fired a 15-inch shell at a piece of
tissue paper and it cam back and hit you.
http://waowen.screaming.net/revision/nuclear/rsanim.htm
Atomic Spectra
Hydrogen
Helium
Mercury
Neon
The Hydrogen Spectrum
Johann Jakob Balmer (1825 - 1898)
Johannes Rydberg (1854 – 1919)
WalterRitz (1878 – 1909)
Ritz Combination Principle
The sum of the frequencies of two spectral lines equals
the frequency of a third.
The Complete Hydrogen Spectrum
Lyman Lines
Balmer Lines
Paschen Lines
Energy Diagram for the Hydrogen Atom
Bohr Model of the Hydrogen Atom
Neils Bohr (1885 – 1962)
Matter Waves
Louis de Broglie (1892 – 1987)
l = h/p
Electron Diffraction Observed in 1927
Crystalline Nickel as an Electron Target
L. H. Germer
C. J. Davisson
…studying electron scattering from a nickel target at Bell Laboratories. After heating
the target to remove an oxide coating that had accumulated during an accidental
break in the vacuum system, they found that the scattered-electron intensity as a
function of the scattering angle showed maxima and minima. Their target had
crystallized, and by accident they had observed electron diffraction.
Physics by Paul A. Tipler
Electron as “Orbiting” Wave
Constructive Interference
(Standing Wave)
Destructive Interference
http://www.youtube.com/watch?v=_S7-PDF6Vzc
Quantized “Orbits” Due To Standing Wave Req.
Now What?
The wave function contains all possible
information about a system, so instead of
speaking of “the state described by the
wave function Y,” we simply say “the
state Y.”
Quantum Chemistry by Ira N. Levine
Erwin Schrodinger (1887 – 1961)
What is the Wave Function?
Quantum mechanics does not say that an electron is
distributed over a large region of space as a wave is
distributed. Rather, it is the probability patterns
(wave functions) used to describe the electron’s
motion that behave like waves and satisfy a wave
equation.
Quantum Chemistry by Ira N. Levine
Max Born (1882 – 1970)