Before the atom electron states were known, spectroscopists saw distintive series in atom spectra, and so they asigned letters to characteristic spectra. These letters were later associated with the azimuthal quantum number l. The first four letters were chosen from properties of the spectra. Letters after "f" follow the alphabetical order (letter "j" is omitted, though).

letter	name	l
s	sharp	0
p	principal	1
d	diffuse	2
f	fundamental	3
g	(from here, it follows the alphabetic order)	4
h		5
...		...

The spectroscopic notation is used in the electron configuration and to create the term symbol for the electron states in a multi-electron atom. The above scheme for a single electron's orbital quantum number is applied to the total orbital angular momentum associated to each electron state.

See also

• principal quantum number
• azimuthal quantum number
• electronic configuration

External links

spectroscopic notation