{"id":541,"date":"2022-09-02T09:44:10","date_gmt":"2022-09-02T09:44:10","guid":{"rendered":"https:\/\/alaskaglobe.com\/?p=541"},"modified":"2023-06-01T06:00:15","modified_gmt":"2023-06-01T06:00:15","slug":"uv-visible-spectroscopy","status":"publish","type":"post","link":"https:\/\/alaskaglobe.com\/uv-visible-spectroscopy\/","title":{"rendered":"UV Visible Spectroscopy"},"content":{"rendered":"\n

UV Visible Spectroscopy:<\/h2>\n\n\n\n

UV Visible Spectroscopy or Ultraviolet-Visible Spectroscopy involves the transitions of electrons within a molecule from a lower electronic energy level to a high energy level or vice-versa by the absorption or emission of radiations in the UV-Visible range of electromagnetic radiations.<\/p>\n\n\n\n

As the electronic energy levels are quantized therefore a discrete line should appear in the spectra for every transition. But a discrete line is not obtained because electronic transitions are accompanied by vibrational and rotational transitions. It leads to the appearance of bands in the electronic spectra of simple molecules.<\/p>\n\n\n\n

When the molecules absorb UV or Visible light, their electrons get promoted from the ground state to the high energy state. In the ground state, the spins of the electrons in each molecular orbital are essentially paired. In the higher energy state, if the spins of the electrons are paired, then it is called an excited singlet state<\/em><\/strong>. On the other hand, if the spins of the electrons in the excited state are parallel, then it is called an excited triplet state<\/em><\/strong>. The triplet state is always lower in energy than the corresponding excited singlet state. In the triplet excited state, electrons are farther apart in space and thus electron-electron repulsion is minimized.<\/p>\n\n\n\n

When the molecule absorbs UV or, visible light, its electrons get promoted from the ground state to the higher energy state. In the ground state, the spins of the electrons are generally paired. The spin multiplicity can be calculated by the following formula.<\/p>\n\n\n\n

Spin selection formula:<\/strong>
S= 2s + 1
S \u2192 Spin multiplicity
s \u2192 Spin quantum number<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
In the case of the parallel form:<\/strong>
S = 2 (1) + 1 (Magnitude of spin quantum number is 1)
S = 3 (Triplet state)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
In the case of antiparallel form:<\/strong>
S = 2(0) + 1 (Magnitude of spin quantum number is zero)
S = 1 (singlet state)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Normally, the absorption of the UV or Visible light results in a singlet ground state to singlet excited state transition i.e. excitation proceeds with the retention of spins. An excited singlet state is converted to an excited triplet state with the emission of energy as light. The absorption of UV or Visible light shifts the electrons from the ground state to the excited states as shown in the figure.<\/p>\n\n\n

\n
\"shows<\/figure><\/div>\n\n\n
The energy difference between the two energy states is as,
\u0394E = h\u03bd
\u0394E = E1<\/sub> – E0<\/sub>
E1<\/sub> \u2192 Energy of the excited state
E0<\/sub> \u2192 Energy of the ground state

We know, Etotal<\/sub> = Eele.<\/sub> + Evib.<\/sub> + Erot.<\/sub>

The approximate magnitude of energy is:
\u0394Eele.<\/sub> = \u0394Evib.<\/sub> x 103<\/sup> = Erot.<\/sub> x 106<\/sup><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

The absorption in the UV region involves a single electronic transition from the lower energy state to the higher energy state containing a single discrete line. But in actuality, a broad spectrum is obtained. The reason for the broad spectrum is that electronic transitions are also accompanied by a large number of possible rotational and vibrational transitions because the energy required for these transitions is less. For this reason, the spectra of simple molecules in the gaseous state contain narrow absorption peaks where each peak represents a transition from a combination of vibrational; and rotational levels in the electronic ground state to the excited state. In complex molecules, where molecules contain a large number of atoms the discrete bands coalesce to produce broad absorption bands.<\/p>\n\n\n\n

\n\n\n\n
Ecosystem<\/a>
Hydrological Cycle or Water Cycle<\/a>
Read More About UV Visible Spectroscopy or Ultraviolet-Visible Spectroscopy<\/a>– Wikipedia<\/td><\/tr><\/tbody><\/table><\/figure>\n","protected":false},"excerpt":{"rendered":"

UV Visible Spectroscopy: UV Visible Spectroscopy or Ultraviolet-Visible Spectroscopy involves the transitions of electrons within a molecule from a lower electronic energy level to a high energy level or vice-versa by the absorption or emission of radiations in the UV-Visible range of electromagnetic radiations. As the electronic energy levels are quantized therefore a discrete line […]<\/p>\n","protected":false},"author":6,"featured_media":584,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"footnotes":""},"categories":[146],"tags":[31],"jetpack_featured_media_url":"https:\/\/alaskaglobe.com\/wp-content\/uploads\/2022\/09\/UV-Visible-Spectroscopy.jpg","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"_links":{"self":[{"href":"https:\/\/alaskaglobe.com\/wp-json\/wp\/v2\/posts\/541"}],"collection":[{"href":"https:\/\/alaskaglobe.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/alaskaglobe.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/alaskaglobe.com\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/alaskaglobe.com\/wp-json\/wp\/v2\/comments?post=541"}],"version-history":[{"count":0,"href":"https:\/\/alaskaglobe.com\/wp-json\/wp\/v2\/posts\/541\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/alaskaglobe.com\/wp-json\/wp\/v2\/media\/584"}],"wp:attachment":[{"href":"https:\/\/alaskaglobe.com\/wp-json\/wp\/v2\/media?parent=541"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/alaskaglobe.com\/wp-json\/wp\/v2\/categories?post=541"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/alaskaglobe.com\/wp-json\/wp\/v2\/tags?post=541"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}