Atomic physics experiments

atomic and nuclear physics ppt and atomic physics lecture notes+ppt
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Published Date:23-07-2017
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Atomic Physics rd 3 year B1 P. Ewart Oxford Physics: 3rd Year, Atomic Physics• Lecture notes • Lecture slides • Problem sets All available on Physics web site: http:www.physics.ox.ac.uk/users/ewart/index.htm Oxford Physics: 3rd Year, Atomic PhysicsAtomic Physics: • Astrophysics • Plasma Physics • Condensed Matter • Atmospheric Physics • Chemistry •Biology Technology • Street lamps • Lasers • Magnetic Resonance Imaging • Atomic Clocks • Satellite navigation: GPS •etc Oxford Physics: 3rd Year, Atomic PhysicsAstrophysicsCondensed Matter Zircon mineral crystal C Fullerene 60Snow crystalLasersBiology DNA strandLecture 1 • How we study atoms: – emission and absorption of light – spectral lines • Atomic orders of magnitude • Basic structure of atoms – approximate electric field inside atoms Oxford Physics: 3rd Year, Atomic Physicsψ ψ 1 2 Atomic radiation ψ(t) = ψψ + 12 Ψ(τ t+ ) Ψ(t) 2 2 IΨ(t)I I Ψ(t + τ)I Oscillating charge cloud: Electric dipole Oxford Physics: 3rd Year, Atomic PhysicsSpectral Line Broadening Homogeneous e.g. Lifetime (Natural) Collisional (Pressure) Inhomogeneous e.g. Doppler (Atomic motion) Crystal Fields Oxford Physics: 3rd Year, Atomic PhysicsLifetime (natural) broadening Intensity spectrum Number of excited atoms Electric field amplitude N(t) I(ω) E(t) Fourier Transform frequency, ω Time, t Exponential decay Lorentzian lineshape Oxford Physics: 3rd Year, Atomic PhysicsLifetime (natural) broadening Intensity spectrum Number of excited atoms Electric field amplitude N(t) I(ω) E(t) -8 8 `τ 10 s `Δν 10 Hz frequency, ω Time, t Exponential decay Lorentzian lineshape Oxford Physics: 3rd Year, Atomic PhysicsCollision (pressure) broadening Intensity spectrum Number of uncollided atoms N(t) I(ω) frequency, ω Time, t Exponential decay Lorentzian lineshape Oxford Physics: 3rd Year, Atomic PhysicsCollision (pressure) broadening Intensity spectrum Number of uncollided atoms N(t) I(ω) -10 10 `τ 10 s `Δν 10 Hz c frequency, ω Time, t Exponential decay Lorentzian lineshape Oxford Physics: 3rd Year, Atomic PhysicsDoppler (atomic motion) broadening Distribution of atomic speed Doppler broadening N(v) I(ω) frequency, ω atomic speed, v Maxwell-Boltzmann Gaussian lineshape distribution 9 ` Typical Δν 10 Hz Oxford Physics: 3rd Year, Atomic PhysicsAtomic orders of magnitude -19 Atomic energy: 10 J → 2 eV 1 Thermal energy: / eV 40 Ionization energy, H: 13.6 eV -1 = Rydberg Constant 109,737 cm -11 Atomic size, Bohr radius: 5.3 x 10 m Fine structure constant, α = v/c: 1/137 -24 -1 Bohr magneton, μ : 9.27 x 10 JT B Oxford Physics: 3rd Year, Atomic PhysicsThe r Central Field 1/r Z/r U(r) “Actual” Potential Oxford Physics: 3rd Year, Atomic PhysicsZ eff Important Z region 1 Radial position, r Oxford Physics: 3rd Year, Atomic Physics