Quantum Processes in Astrophysics
In Chapter 6, we considered the means by which particles could absorb or emit radiation. But we restricted ourselves to processes in which the Maxwell field equations of classical electrodynamics could be applied. These equations break down on the scale of atomic systems. The electron bound to a positively charged nucleus does not lose energy because of its accelerated motion, although the classical theory of radiation predicts that it should. Instead, the ground state of hydrogen, or any atom, is stable for an indefinitely long period. Moreover, when energy is actually radiated from excited states, and the atomic ground energy state is finally reached, we always find that only discrete amounts of energy have been given off in each transition. Again, this is at variance with classical predictions.
KeywordsAngular Momentum Absorption Cross Section Atomic System Equivalent Width Principal Quantum Number
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