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Spin and Atomic Physics. Today. HW 8, problem 7.38 Quiz 11.6 Topics in this chapter: The spin and the Stern-Gerlach experiment. Fermion, Boson and the Pauli exclusion principle. Multi-electron atoms and the Periodic Table. Characteristic X-rays. HW problem 7.38.
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Spin and Atomic Physics Today HW 8, problem 7.38 Quiz 11.6 Topics in this chapter: The spin and the Stern-Gerlach experiment. Fermion, Boson and the Pauli exclusion principle. Multi-electron atoms and the Periodic Table. Characteristic X-rays.
HW problem 7.38 Since it is an attractive central force and the angular momentum is given:
The Stern-Gerlach experiment in the history of QM The Balmer series 656 nm 410 nm 434 nm 486 nm 1885 Empirical formula in 1885: Electron discovered in by J.J. Thomson in 1897 1897 Rutherford discovered nucleus in 1909 1909 1913 Niels Bohr’s Hydrogen model in 1913 Stern-Gerlach experiment, electron spin in 1922 1922 The de Broglie wave (1924): The Schrödinger Equation (1926): 1924 1926
The Stern-Gerlach experiment Interesting to read: http://scitation.aip.org/journals/doc/PHTOAD-ft/vol_56/iss_12/53_1.shtml
The Stern-Gerlach experiment Classical Quantum observed WOW !
The Stern-Gerlach experiment Quantum But: From: When ground state: But this was observed: WOW !!! What is this?
Spin, an intrinsic property Spin: an intrinsic magnetic dipole moment of particles like electron, proton and photons. This dipole moment is related to an intrinsic angular momentum. The symbol is S, which is like L the orbital angular momentum. The corresponding quantum number is s. The spin magnetic dipole moment is Spin is an intrinsic property of a particle like mass and charge. Example 8.1 electron
Fermions and Bosons Spin is an intrinsic property of a particle like mass and charge. Fermions Bosons (half-integral spin) (integral spin) Particle s Particle s Electron, e- ½ Pion, π0 0 Proton, p ½ Alpha 0 Neutron, n ½ Photon, γ1 Neutrino, ν½ Deuteron, d 1 Omega, Ω-½ Graviton 2
The building blocks for our Universe Spin is an intrinsic property of a particle like mass and charge.
The Pauli exclusion principle The Pauli exclusion principle (1924): No two indistinguishable fermions may occupy the same individual particle state. This principle applies only to fermions in In an atom, or an isolated system like a molecule. This principle does not apply to bosons.
Review questions • What is the spin of a particle in CM and in QM? • Give one example in each the Pauli exclusion principle is applied.
Preview for the next class (11/11) • Text to be read: • 8.4 and 8.5 • Questions: • Why we have H2 as hydrogen molecules while Ne as neon molecules? • What is the energy ordering of electron states in an atom with Z = 30? Can you fill the electrons for the element Zn if asked for?
Homework 12, due by 11/13 Problems 8.28, 8.31 on page 339. Read section 8.2 and 8.3 one more time and see if you can answer questions in problem 8.7 on page 338.