3P2

3P2, often written as ^3P2 in spectroscopic notation, is a term symbol used in atomic spectroscopy to designate a specific electronic energy level of an atom or ion. The notation ^{2S+1}L_J encodes three quantum numbers: S is the total electron spin, L is the total orbital angular momentum (S=0, P=1, D=2, F=3, etc.), and J is the total angular momentum. For 3P2, the multiplicity is 3, indicating S=1; L is P (L=1); J equals 2. Therefore 3P2 denotes a triplet P state with total angular momentum J=2.

This term can arise for many-electron atoms and ions with suitable electron configurations, and its exact energy depends on the arrangement of electrons and the coupling scheme (LS coupling is common for lighter elements). The label provides a concise way to reference an energy level in spectroscopic data and theoretical calculations.

Applications of the 3P2 designation appear in the classification of spectral lines, modeling of plasmas, and interpretation of astrophysical spectra. Researchers use term symbols to predict allowed transitions between levels, guided by selection rules. For electric dipole transitions, common rules include no change in spin (ΔS=0), ΔL=0 or ±1, and ΔJ = 0, ±1 with the restriction that J=0↔J=0 is forbidden. These rules help determine which spectral lines may appear and their relative intensities.

Notes: the symbol is routinely written as ^3P2, and appears across atomic, molecular, and plasma spectroscopy literature. See also: term symbol, atomic spectroscopy, selection rules.