PHYS 17200 Lecture Notes - Lecture 15: Stimulated Emission, Spontaneous Emission, Photon
25 Mar 2015
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Phys 17200 - modern mechanics - lecture 15_energy quantization. Discrete packets of electromagnetic energy and momentum that travel at the speed of light. There is a wave-particle character to the explanation of the discrete internal energy states of atoms as well. Quantum model of the interaction between atom"s charged particles and it"s. External photon causes electron jump to lower energy level. Lasers contain atomic oscillators that emit identical photons, with the same energy, phase, direction . The excited atom could spontaneously decay and emit a photon, at some random time. A photon of energy equal to the excited state can stimulate the atomic oscillator to emit its photon in phase with the resonant driving photon. If there are many atoms in the same excited state, there can be a cascade or chain reaction that greatly multiplies the number of stimulated photons . However, ground state absorption can quench this effect.
