Terms sourced from: http://iupac.org/publications/pac/67/11/1913/

"Nomenclature, symbols, units, and their usage in spectrochemical analysis-XV. Laser-based molecular spectroscopy for chemical analysis - laser fundamentals (IUPAC Recommendations 1995)", Moore, D.S.;Vo-dinh, T.;Velthorst, N.H.;Schrader, B., Pure and Applied Chemistry 1995, 67(11), 1913