{"id":59,"date":"2019-09-18T16:19:30","date_gmt":"2019-09-18T20:19:30","guid":{"rendered":"https:\/\/sites.bu.edu\/murdock-hart\/?page_id=59"},"modified":"2019-10-03T11:26:30","modified_gmt":"2019-10-03T15:26:30","slug":"airglow","status":"publish","type":"page","link":"https:\/\/sites.bu.edu\/murdock-hart\/airglow\/","title":{"rendered":"Atmospheric Airglow"},"content":{"rendered":"<p style=\"text-align: justify;\">The Earth\u2019s atmosphere absorbs and emits radiation. The most significant emission in the optical and near-infrared (NIR) is due to the ro-vibrational transitions of the OH molecule. OH is created in the ozone hydration process, H + O<sub>3\u00a0<\/sub>&#8211;&gt; OH + O<sub>2<\/sub>, and is formed in a vibrationally excited state. The vibrationally excited molecule is relaxed through collisional quenching and radiation emission. The figure below is a Sloan Digital Sky Survey (SDSS) Baryon-Acousitc Oscillation Spectroscopic Survey (BOSS) sky spectrum which has been annotated to highlight the OH transitions.<\/p>\n<p><img loading=\"lazy\" src=\"\/murdock-hart\/files\/2019\/09\/sky_schematic-636x378.png\" alt=\"\" class=\"size-medium wp-image-60 aligncenter\" width=\"636\" height=\"378\" srcset=\"https:\/\/sites.bu.edu\/murdock-hart\/files\/2019\/09\/sky_schematic-636x378.png 636w, https:\/\/sites.bu.edu\/murdock-hart\/files\/2019\/09\/sky_schematic-768x457.png 768w, https:\/\/sites.bu.edu\/murdock-hart\/files\/2019\/09\/sky_schematic-1024x609.png 1024w, https:\/\/sites.bu.edu\/murdock-hart\/files\/2019\/09\/sky_schematic.png 1723w\" sizes=\"(max-width: 636px) 100vw, 636px\" \/><\/p>\n<p style=\"text-align: justify;\">The OH spectrum has a band head structure show in the figure below. The excited vibrational states of the OH molecule are accompanied by a range of rotational states, and the vibrational transitions can be accompanied by rotational changes in state. The change in rotational quantum number can be -1, 0, or +1 giving rise to the R, Q, and P branches of the OH emission spectrum. The energy levels of the OH molecule also experience spin orbit splitting leading to the F<sub>1<\/sub> and F<sub>2<\/sub> electronic states. The energy levels of the OH molecule are also inverted because the higher total angular momentum of the F<sub>1<\/sub> electronic states are lower in energy than the F<sub>2<\/sub> states.<\/p>\n<p><img loading=\"lazy\" src=\"\/murdock-hart\/files\/2019\/09\/SDSS_OH_7_3_mean_sky_spectrum_extended-636x357.png\" alt=\"\" class=\"size-medium wp-image-114 aligncenter\" width=\"636\" height=\"357\" srcset=\"https:\/\/sites.bu.edu\/murdock-hart\/files\/2019\/09\/SDSS_OH_7_3_mean_sky_spectrum_extended-636x357.png 636w, https:\/\/sites.bu.edu\/murdock-hart\/files\/2019\/09\/SDSS_OH_7_3_mean_sky_spectrum_extended-768x431.png 768w, https:\/\/sites.bu.edu\/murdock-hart\/files\/2019\/09\/SDSS_OH_7_3_mean_sky_spectrum_extended-1024x575.png 1024w, https:\/\/sites.bu.edu\/murdock-hart\/files\/2019\/09\/SDSS_OH_7_3_mean_sky_spectrum_extended.png 1230w\" sizes=\"(max-width: 636px) 100vw, 636px\" \/><\/p>\n<p style=\"text-align: justify;\">The OH spectrum increase in intensity at the lower vibrational transitions, and peaks around 17,000 A. The spectrum below is a model OH spectrum.<\/p>\n<p><img loading=\"lazy\" src=\"\/murdock-hart\/files\/2019\/09\/simulated_OH_spectrum-636x371.png\" alt=\"\" class=\"size-medium wp-image-152 aligncenter\" width=\"636\" height=\"371\" srcset=\"https:\/\/sites.bu.edu\/murdock-hart\/files\/2019\/09\/simulated_OH_spectrum-636x371.png 636w, https:\/\/sites.bu.edu\/murdock-hart\/files\/2019\/09\/simulated_OH_spectrum-768x448.png 768w, https:\/\/sites.bu.edu\/murdock-hart\/files\/2019\/09\/simulated_OH_spectrum-1024x597.png 1024w, https:\/\/sites.bu.edu\/murdock-hart\/files\/2019\/09\/simulated_OH_spectrum.png 1200w\" sizes=\"(max-width: 636px) 100vw, 636px\" \/><\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The Earth\u2019s atmosphere absorbs and emits radiation. The most significant emission in the optical and near-infrared (NIR) is due to the ro-vibrational transitions of the OH molecule. OH is created in the ozone hydration process, H + O3\u00a0&#8211;&gt; OH + O2, and is formed in a vibrationally excited state. The vibrationally excited molecule is relaxed [&hellip;]<\/p>\n","protected":false},"author":16674,"featured_media":0,"parent":0,"menu_order":34,"comment_status":"closed","ping_status":"closed","template":"","meta":[],"_links":{"self":[{"href":"https:\/\/sites.bu.edu\/murdock-hart\/wp-json\/wp\/v2\/pages\/59"}],"collection":[{"href":"https:\/\/sites.bu.edu\/murdock-hart\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/sites.bu.edu\/murdock-hart\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/sites.bu.edu\/murdock-hart\/wp-json\/wp\/v2\/users\/16674"}],"replies":[{"embeddable":true,"href":"https:\/\/sites.bu.edu\/murdock-hart\/wp-json\/wp\/v2\/comments?post=59"}],"version-history":[{"count":11,"href":"https:\/\/sites.bu.edu\/murdock-hart\/wp-json\/wp\/v2\/pages\/59\/revisions"}],"predecessor-version":[{"id":204,"href":"https:\/\/sites.bu.edu\/murdock-hart\/wp-json\/wp\/v2\/pages\/59\/revisions\/204"}],"wp:attachment":[{"href":"https:\/\/sites.bu.edu\/murdock-hart\/wp-json\/wp\/v2\/media?parent=59"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}