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* [[Scandium]] atom: <math>\scriptstyle  ^2D_{\frac{3}{2}}\,</math>. Spin angular momentum: ''S'' = 1/2. Orbital angular momentum: ''L'' = 2. Spin-orbital angular momentum: ''J'' = 3/2. Electronic configuration: [Ne]3''s''<sup>2</sup>3''p''<sup>6</sup>3''d''<sup>1</sup>4''s''<sup>2</sup>. Parity even.
* [[Scandium]] atom: <math>\scriptstyle  ^2D_{\frac{3}{2}}\,</math>. Spin angular momentum: ''S'' = 1/2. Orbital angular momentum: ''L'' = 2. Spin-orbital angular momentum: ''J'' = 3/2. Electronic configuration: [Ne]3''s''<sup>2</sup>3''p''<sup>6</sup>3''d''<sup>1</sup>4''s''<sup>2</sup>. Parity even.
==External link==
[http://physics.nist.gov/Pubs/AtSpec/node09.html NIST Atomic Sectroscopy]


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Revision as of 08:01, 10 January 2008

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In atomic spectroscopy, a term symbol gives the total spin-, orbital-, and spin-orbital angular momentum of the atom. The term symbol has the following form:

where S is the total spin angular momentum and 2S+1 is the spin multiplicity. The symbol X represents the total orbital angular momentum. For historical reasons it is coded by a letter as follows (between brackets the L quantum number designated by the letter):

and further up the alphabet (excluding P and S). The value J is the quantum number of the spin-orbital angular momentum: JL + S. The value J satisfies the triangular conditions:

.

Sometimes the parity of the state is added, as in

which indicates that the state has odd parity. This is the case if the sum of the one-electron orbital angular momenta is odd.

For historical reasons, the term symbol is somewhat inconsistent in the sense that the quantum numbers L and J are indicated directly, by a letter and a number, respectively, while the spin S is indicated by its multiplicity 2S+1. The eigenstates labeled by a term symbol are obtained in the Russell-Saunders coupling scheme.

[edit intro]

Examples

A few ground state atoms are listed.

  • Hydrogen atom: . Spin angular momentum: S = 1/2. Orbital angular momentum: L = 0. Spin-orbital angular momentum: J = 1/2. Electronic configuration: 1s. Parity: even.
  • Carbon atom: . Spin angular momentum: S = 1. Orbital angular momentum: L = 1. Spin-orbital angular momentum: J = 0. Electronic configuration: [He]2s22p2. Parity even.
  • Aluminium atom: . Spin angular momentum: S = 1/2. Orbital angular momentum: L = 1. Spin-orbital angular momentum: J = 1/2. Electronic configuration: [Ne]3s23p1. Parity odd.
  • Scandium atom: . Spin angular momentum: S = 1/2. Orbital angular momentum: L = 2. Spin-orbital angular momentum: J = 3/2. Electronic configuration: [Ne]3s23p63d14s2. Parity even.

External link

NIST Atomic Sectroscopy