Ultraviolet-visible spectroscopy chromophore

Chromophore (Section 13 21) The structural unit of a mole cule principally responsible for absorption of radiation of a particular frequency a term usually applied to ultraviolet visible spectroscopy... 

Table 7.9 Electronic Absorption Bands for Representative Chromophores Table 7.10 Ultraviolet Cutoffs of Spectrograde Solvents Table 7.11 Absorption Wavelength of Dienes Table 7.12 Absorption Wavelength of Enones and Dienones Table 7.13 Solvent Correction for Ultraviolet-Visible Spectroscopy Table 7.14 Primary Bands of Substituted Benzene and Heteroaromatics Table 7.15 Wavelength Calculation of the Principal Band of Substituted Benzene Derivatives...

J.A. Schmidt, Ultraviolet/visible spectroscopy of chromophores in mechanical pnlps, in Encyclopedia of Analytical Chemistry, John Wiley Sons Ltd, Chichester, 8388-8406 (2000). 

Ultraviolet-visible (UV-vis) spectroscopy gives less distinct information about the molecular structure than infrared and Raman spectroscopies. Typically, the bands appearing in UV-vis spectra are rather broad. This is because of the simultaneous excitation of rotational, vibrational, and electronic transitions. The bands appearing in the UV-vis spectra of organic molecules are prominent for chromophores. These chromophores can be small parts of the sample molecule, but in extreme cases also the complete electronic shell of the sample molecule. 

Ultraviolet-visible (UV-Vis) spectroscopy UV-Vis spectroscopy, like FTIR, is a technique which is useful in the identification of pure drug compounds. Different compounds contain chromophores, which will absorb specific wavelengths of UV or visible... 

These devices are based on the anisotropic absorption of light. Usually molecular crystals exhibit this property and tourmaline is the classical example for this. For practical purposes, however, micro crystals are oriented in polymer sheets. Polymers containing chromophors become after stretching dichroic polarizers. The devices produced in this manner are called polawids. They have found a broad application in many technologies. Their application in spectroscopy is limited to the near ultraviolet and to the visible and near infrared range of the spectrum. In vibrational spectroscopy polaroids are employed as analyzers only for Raman spectroscopy. 

The theory underlying electronic spectroscopy with lasers is essentially the theory of visible or ultraviolet photon interactions. The distinctive features that arise with the deployment of laser light in electronic spectroscopy are principally those that relate to or exploit the qualities of the electric field produced by the laser beam. Laser electronic spectroscopy is primarily based on coupling (usually of dipolar character) between the electron clouds of individual ions, atoms, chromophores or molecules of the sample with the electric field of the impinging laser radiation. The high level of monochromaticity affords the means to obtain high-resolution data. 

Ultraviolet and visible light absorption spectroscopy can be used to identify chromophores (e.g. benzene rings and carbonyl groups) and to determine the lengths of sequences of conjugated multiple bonds in polymers. It also can be used to analyse polymers for the presence of additives such as antioxidants or for detection of residual monomer(s). Additionally, fluorescence and phosphorescence techniques are important in studies of polymer photophysics. 

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