Effect of conjugation on absorption maximum

The Π−Π* transition of ethylene requires of light at 171 nm (164 kcal/mole), slightly into the vacuum ultraviolet region. In conjugated  Fig.1.1 in 1,3-butadiene, the Π−Π* transition absorbs at a wavelength of 217 nm  (219 kcal (mole) or 540 kj/mole), compared with 171 nm (164 kcal/mole or 686 kj/mole) for ethylene. this.This longer-wavelength(lower energy) absorption result … Read moreEffect of conjugation on absorption maximum

The UV Spectrum -Spectroscopy

Absorption of radiations in UV- visible range (λ 1nm to 800nm) causes electronic excitations. The electron are excited from their ground state to higher excitations states by absorbing the proper radiation. Since UV-visible spectroscopy involves electronic transitions, it is often called electronic spectroscopy. The intensity of absorption of radiations as a functions of wavelength of … Read moreThe UV Spectrum -Spectroscopy

Electromagnetic Spectrum and Origin of Absorption Spectra

Visible light is one from of the energy generally known as electromagnetic radiation. Other common forms of electromagnetic radiation are X-rays; ultraviolet radiation (UV, the radiation from the sun);infrared radiation (IR, the radiation from a heat source); microwaves (used in radar and in the microwave open); and radio waves (used to carry radio and television … Read moreElectromagnetic Spectrum and Origin of Absorption Spectra

Designation of Adsorption Bands

UV-visible absorption bonds may be designed by the type of the of electronic transition from which they originate, e.g.., σ →σ* band , Π→Π* band, etc. or by letter designation. The following letter designation was proposed because more than one band may arise due to the same type of electronic transition. 1) K-bands (German:Konjugierte= conjugated):  These bands originated from Π→Π*  transition in compounds having … Read moreDesignation of Adsorption Bands

Absorption Spectroscopy & its Graphical Representation

Absorption Spectra

Experimental Arrangement in Absorption Spectroscopy The most common type of spectroscopy used for structure determination is called absorption spectroscopy. The basis of absorption spectroscopy is that substance absorbs energy from the certain wavelength of electromagnetic radiation.  In an absorption spectroscopy experiment, this absorption is determined as a function of wavelength, frequency or energy in an instrument called spectrophotometer or … Read moreAbsorption Spectroscopy & its Graphical Representation