|
In quantum mechanics, the term symbol is an abbreviated description of the angular momentum quantum numbers in a multi-electron atom. Each energy level of a given electron configuration is described by its own term symbol, assuming LS coupling (also known as Russell-Saunders coupling). The ground state term symbol is predicted by Hund's rules. Tables of atomic energy levels identified by their term symbols have been compiled by the National Institute of Standards and Technology. In this database, neutral atoms are identified as I, singly ionized atoms as II, etc.〔 ==LS coupling and symbol== For light atoms, the spin-orbit interaction (or coupling) is small so that the total orbital angular momentum ''L'' and total spin ''S'' are good quantum numbers. The interaction between ''L'' and ''S'' is known as ''LS coupling'' or ''Russell-Saunders'' coupling. Atomic states are then well described by term symbols of the form ::2''S''+1''L''''J'' where :''S'' is the total spin quantum number. 2''S'' + 1 is the spin multiplicity: the maximum number of different possible states of ''J'' for a given (''L'', ''S'') combination. :''J'' is the total angular momentum quantum number. :''L'' is the total orbital quantum number in spectroscopic notation. The first 17 symbols of L are: The nomenclature (''S'', ''P'', ''D'', ''F'') is derived from the characteristics of the spectroscopic lines corresponding to (''s'', ''p'', ''d'', ''f'') orbitals: sharp, principal, diffuse, and fundamental; the rest being named in alphabetical order. When used to describe electron states in an atom, the term symbol usually follows the electron configuration. For example, one low-lying energy level of the carbon atom state is written as 1''s''22''s''22''p''2 3''P''2. The superscript 3 indicates that the spin state is a triplet, and therefore ''S'' = 1 (2''S'' + 1 = 3), the ''P'' is spectroscopic notation for ''L'' = 1, and the subscript 2 is the value of ''J''. Using the same notation, the ground state of carbon is 1''s''22''s''22''p''2 3''P''0.〔(NIST Atomic Spectrum Database ) To read neutral carbon atom levels for example, type "C I" in the Spectrum box and click on Retrieve data.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「term symbol」の詳細全文を読む スポンサード リンク
|