Editing Spectral line (section)

==== Natural broadening ====
The lifetime of excited states results in natural broadening, also known as lifetime broadening. The [[uncertainty principle]] relates the lifetime of an excited state (due to [[Spontaneous emission|spontaneous radiative decay]] or the [[Auger effect|Auger process]]) with the uncertainty of its energy. 
Some authors use the term "radiative broadening" to refer specifically to the part of natural broadening caused by the spontaneous radiative decay.<ref>{{Cite book| publisher = Wiley| isbn = 978-0-471-12533-4| last1 = Krainov| first1 = Vladimir| last2 = Reiss| first2 = Howard| last3 = Smirnov| first3 = Boris| title = Radiative Processes in Atomic Physics| date = 1997| doi = 10.1002/3527605606}}</ref>
A short lifetime will have a large energy uncertainty and a broad emission. This broadening effect results in an unshifted [[Lorentzian function|Lorentzian profile]]. The natural broadening can be experimentally altered only to the extent that decay rates can be artificially suppressed or enhanced.<ref>For example, in the following article, decay was suppressed via a microwave cavity, thus reducing the natural broadening: {{cite journal|last=Gabrielse|first=Gerald|author2=H. Dehmelt |title=Observation of Inhibited Spontaneous Emission|journal=Physical Review Letters|volume=55|pages=67–70|year=1985|doi=10.1103/PhysRevLett.55.67|pmid=10031682|issue=1|bibcode=1985PhRvL..55...67G}}</ref>