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Learn about quantum numbers, LS coupling, term symbols, microstate analysis for atomic term symbols, and more in multielectron atoms. Dive into angular momentum in atoms & construct term symbols. Explore the emission & absorption spectrum of sodium.
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Last hour: Angular momentum in multielectron atoms • Total orbital angular momentum: quantum numbers: L, ML • Total spin: quantum numbers: S, MS • Total angular momentum: quantum numbers: J = L+S, …. , |L-S| in steps of 1; MJ = -J, …, +J • Levels of the same L terms L = 0, 1, 2, 3, 4 S, P, D, F, G • LS coupling: for small Z, neglect spin-orbit coupling makes total orbital, total spin, total angular momentum conserved L, S, J are “good quantum numbers”, can be used to label terms • All terms have different energies • Atomic term symbols: 2S+1LJ • Microstate analysis to construct allowed term symbols
Microstate Analysis for Constructing Atomic Term Symbols Step 1: Write down all possible values for L and S according to the electron configuration. Step 2: Construct a microstate table, containing all possible combinations of ML and MS, and fill it with microstates that can produce these combinations. Step 3: Identify states that are excluded due to the Pauli principle, and strike them from the table. Step 4: To obtain the first term symbol, identify the highest ML in the table, and the highest MS that belongs to this ML. The highest ML value will determine L of the term, and the MS belonging to it determines S. Strike one microstate from the table for each ML/MS combination that is part of the term. Step 5: Repeat Step 4 with the new (reduced) table until no more microstates are left.
John Robinson Pierce, American engineer and author. Coined the term "transistor”, wrote science fiction under the pseudonym “J.J. Coupling”