Editing Spectral line (section)

==Nomenclature{{anchor|nomencature_anchor}}==
Strong spectral lines in the [[visible spectrum|visible part of the electromagnetic spectrum]] often have a unique [[Fraunhofer line]] designation, such as '''K''' for a line at 393.366&nbsp;nm emerging from singly-ionized calcium atom, '''Ca<sup>+</sup>''', though some of the Fraunhofer "lines" are blends of multiple lines from several different [[Chemical species|species]].

In other cases, the lines are designated according to the level of [[ion]]ization by adding a [[Roman numeral]] to the designation of the [[chemical element]]. Neutral atoms are denoted with the [[Roman numeral]] I, singly ionized atoms with II, and so on, so that, for example:

'''Cu II''' {{Em dash}} copper ion with +1 charge, '''Cu<sup>1+</sup>'''

'''Fe III''' {{Em dash}} iron ion with +2 charge, '''Fe<sup>2+</sup>'''

More detailed designations usually include the line [[wavelength]] and may include a [[multiplet]] number (for atomic lines) or [[Molecular spectra or band spectra|band designation]] (for molecular lines). Many spectral lines of atomic [[hydrogen]] also have designations within their respective [[Hydrogen spectral series|series]], such as the [[Lyman series]] or [[Balmer series]]. Originally all spectral lines were classified into series: the ''[[Principal series (spectroscopy)|principal series]]'', ''[[sharp series]]'', and ''[[diffuse series]]''. These series exist across atoms of all elements, and the patterns for all atoms are well-predicted by the [[Rydberg-Ritz combination principle|Rydberg-Ritz formula]]. These series were later associated with suborbitals.