Termos Espectroscópicos: A Linguagem dos Níveis de Energia e das Transições Eletrônicas nos Átomos

Resumo

Determination of the atomic term symbols following LS (Russell-Saunders), jj, and JK coupling schemes
are presented. In the case of LS terms, a sequence of steps involving the building of a table of microstates,
an accounting table of occurrences, and the extraction of the terms is presented. This procedure does
not need to delete invalid terms. In the case of jj and JK terms similar procedures are presented, which
are easy to follow. Examples for carbon, lead and palladium are presented to show the use of LS, jj, and
JK term symbols. The transition from LS to jj coupling is shown for the elements of the Group 14 of the
Periodic Table, indicating that jj coupling is more appropriate to describe the lead energy levels. The
Palladium lowest excited energy levels are presented to show that JK coupling is much more common
than it is generally supposed and it is another coupling scheme which must be known by the chemistry
community, in addition to the jj coupling, which is also not frequently considered.
Keywords: Spectroscopy; spectroscopic terms; LS coupling; jj coupling; JK coupling.