Particles and Waves

Blackbody Radiation Stephan-Boltzman Law T4 Radiance T3 T2 T1 wavelength

Wien’s Law & Blackbody Radiance Wavelength Intensity 6000K 4000K 700nm 400nm Visible IR UV

Photons Light consists of packets or quanta of energy. v Light consists of packets or quanta of energy. Heisenberg’s Uncertainty Principle l v

Photoelectric Effect Electrons are emitted when light is incident on certain metals. IR l=1.0×10-5m UV e- e- l=1.0×10-7m

Atomic Spectra Emission Absorption Hydrogen Specific wavelengths added by hot gas. Absorption Specific wavelengths removed by cold gas. Hydrogen Helium Carbon Oxygen

Bohr Model of Hydrogen Electrons move in circular orbits Only certain orbits are stable Radiation emitted or absorbed as electron moves from one orbit to another Allowed orbits determined by quantized angular momentum

Bohr Model of Hydrogen Electron of the hydrogen atom can only be in specific energy states. p+ n=3 n=1 n=2 g -13.6 eV -3.4 eV -1.5 eV 0 eV Energy Free e-

Matter Waves How can an electron go through two holes at once? g g g

Fundamental Paradox Wave/Particle Duality Electron can be in multiple states at one time. Godel’s Incompleteness Theorem Can not have an all encompassing theory of everything. Finiteness of man

End of Science? Positivism Limitation Progress towards an ultimate understanding of the nature of reality. Limitation All universal models will be incomplete and possibly paradoxical. Does not eliminate the usefulness of the model.

Wave Mechanics DeBroglie Wavelength Schrodinger’s Equation Solution:

Quantum Numbers Principle QN Orbital QN Magnetic QN Spin n=1,2,3,… 3d 4d 5d 6d 4f 5f Principle QN n=1,2,3,… Orbital QN l=0,1,2,…n-1 Magnetic QN ml=-l,…0…+l Spin ms=-1/2,+1/2

Valence Electrons What states are filled by the electons of Ne? n = 4 -1 1 -2 -1 1 2 n = 3 -1 1 -2 -1 1 2 ml n = 2 -1 1 ml n = 1 ml l = 0 l = 1 l = 2

Lasers Light Amplification through Stimulated Emission of Radiation. Ground State E1 E2 Metastable State E2 e- e- e- e- e- e- E1 E0