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Circularly polarized light , absorption circular dichroism

Various optical data (absorption, polarized light absorption, circular dichroism spectra at several different temperatures and photochemical holebuming experiments) are simulated with a version of the model described in Section 2. The detailed results are reported in refs. 3,4 and 9-12. A typical low temperature absorption lineshape is compared to the experimental spectrum in Fig. 1. Other optical spectra are reproduced with a similar quality agreement. [Pg.96]

Circular dichroism (c.d.) spectroscopy measures the difference in absorption between left- and right-circularly polarized light by an asymmetric molecule. The spectrum results from the interaction between neighboring groups, and is thus extremely sensitive to the conformation of a molecule. Because the method may be applied to molecules in solution, it has become popular for monitoring the structure of biological molecules as a function of solvent conditions. [Pg.73]

Ever since Pasteur s work with enantiomers of sodium ammonium tartrate, the interaction of polarized light has provided a powerful, physical probe of molecular chirality [18]. What we may consider to be conventional circular dichroism (CD) arises from the different absorption of left- and right-circularly polarized light by target molecules of a specific handedness [19, 20]. However, absorption measurements made with randomly oriented samples provide a dichroism difference signal that is typically rather small. The chirally induced asymmetry or dichroism can be expressed as a Kuhn g-factor [21] defined as ... [Pg.269]

Optically active chromophores show different absorption for left and right circular polarized light (where the orientation of the polarized light changes periodically). These substances modify a circular polarized beam in such a way that the light is elliptically polarized after leaving the sample, an effect called circular dichroism. [Pg.81]

Several direct methods are available to analyze the tertiary structure of ODNs like nuclear magnetic resonance (NMR) and X-ray crystallographic (XRC) techniques, which needs a sophisticated setup and infrastructure. An alternative but indirect method to study the structure and conformations of nucleic acids is circular dichroism spectroscopy (CD spectroscopy) (25, 26), where circular dichroism refers to the differential absorption of left and right circularly polarized light (27). [Pg.48]

Enantiomers can be distinguished by their rotation of plane-polarized light at a specific wavelength, or over a range of wavelengths (optical rotatory dispersion, ORD), as well as by the difference in absorption of right and left circularly polarized light (circular dichroism. Cotton effect, CD). [Pg.151]

However, (8.25) is not restricted to spheres but holds for particles of arbitrary shape. Thus, circular dichroism in particulate media includes a component that is the result of differential scattering, in contrast with circular dichroism in homogeneous media, which arises solely from differential absorption of left-circularly and right-circularly polarized light. [Pg.193]

Circular dichroism (CD) is a spectroscopic analytical technique used for conformational analysis of peptides and proteins (Johson 1988). It uses the principles of chirality and absorption specifically the different absorption profiles demonstrated by a system for left as opposed to right circularly polarized light. For a system to exhibit CD activity, it must contain a chiral (asymmetric) center that is linked in some way to the chromophore responsible for the absorption. [Pg.154]

Magnetic circular dichroism (MCD) is caused by the difference in the magnitude of photon absorption for left-polarized (a ) and right-polarized ([Pg.40]

This means that the molar extinction coefficients of the two enantiomers (e, and er) are unequal in circularly polarized light. These differences in absorption (e, and er) can be measured as a function of wavelength, and the curves obtained are called circular dichroism curves. They have positive or negative signs (Cotton effect) just as for optical rotatory dispersion curves. [Pg.891]

Circular Dichroism (CD) is the differential absorption of left- and right-circularly polarized light ... [Pg.180]

Circular dichroism is the differential absorption of left- and right-circularly polarized light by a sample with excess of one enantiomer. The effect is usually expressed as the difference between the molar extinction coefficients for left- and right-circularly polarized light (eL(A) and eR(A))... [Pg.209]


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Absorption circularly polarized

Absorption light

Circular polarized light

Circular polarizers

Circularly polarized

Circularly polarized light Polarization

Light Polarization

Polarized circular

Polarized light

Polarizers/Polarization absorptive polarizer

Polarizers/Polarization dichroism

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