Editing Ozone (section)

==Spectroscopic properties==

Ozone is a bent [[triatomic molecule]] with three vibrational modes: the symmetric stretch (1103.157&nbsp;cm<sup>−1</sup>), bend (701.42&nbsp;cm<sup>−1</sup>) and antisymmetric stretch (1042.096&nbsp;cm<sup>−1</sup>).<ref>{{cite journal |title=Ozone |volume=6 |issue=3 |pages=993–1102 |publisher=U.S. Department of Commerce |year=1972 |last1=Shimanouchi |first1=T. |website=NIST: National Institute of Standards and Technology |url=https://webbook.nist.gov/cgi/cbook.cgi?ID=B4000064&Units=SI&Mask=800#ref-1}}</ref> The symmetric stretch and bend are weak absorbers, but the antisymmetric stretch is strong and responsible for ozone being an important minor [[greenhouse gas]]. This IR band is also used to detect ambient and atmospheric ozone although UV-based measurements are more common.<ref>{{cite book |chapter-url=https://www.wmo.int/pages/prog/www/IMOP/publications/CIMO-Guide/Ed2008Up2010/Part-I/WMO8_Ed2008_PartI_Ch16_Up2010_en.pdf |chapter=Chapter 16: Measurement of Ozone |title=Part I: Measurement of Meteorological Variables |last=World Meteorological Organization |archive-url=https://web.archive.org/web/20160331164807/https://www.wmo.int/pages/prog/www/IMOP/publications/CIMO-Guide/Ed2008Up2010/Part-I/WMO8_Ed2008_PartI_Ch16_Up2010_en.pdf |archive-date=31 March 2016}}</ref>

The electromagnetic spectrum of ozone is quite complex. An overview can be seen at the MPI Mainz UV/VIS Spectral Atlas of Gaseous Molecules of Atmospheric Interest.<ref>{{cite web |title=The MPI-Mainz UV/VIS Spectral Atlas of Gaseous Molecules of Atmospheric Interest |last=Max Planck Institute – Mainz |url=https://uv-vis-spectral-atlas-mainz.org/uvvis_data/cross_sections_plots/Ozone/O3_overview_log.jpg}}</ref>

All of the bands are dissociative, meaning that the molecule falls apart to {{nowrap|O + O<sub>2</sub>}} after absorbing a photon. The most important absorption is the Hartley band, extending from slightly above 300&nbsp;nm down to slightly above 200&nbsp;nm. It is this band that is responsible for absorbing UV&nbsp;C in the stratosphere.

On the high wavelength side, the Hartley band transitions to the so-called Huggins band, which falls off rapidly until disappearing by ~360&nbsp;nm. Above 400&nbsp;nm, extending well out into the NIR, are the Chappius and Wulf bands. There, unstructured absorption bands are useful for detecting high ambient concentrations of ozone, but are so weak that they do not have much practical effect.

There are additional absorption bands in the far UV, which increase slowly from 200&nbsp;nm down to reaching a maximum at ~120&nbsp;nm.