Preferred Label : linear dichroism;
Detailed label : linear dichroism (LD);
IUPAC acronym : LD;
IUPAC definition : For a uniaxial sample with sample axis Z is defined as: \[Δ A_{{l}} A_{Z} - A_{Y}\]
where AZ and AY are the absorption spectra measured with the electric vector of linearly
polarized light along and perpendicular to the sample axis, respectively. For an isotropic
sample ΔAl 0.;
Scope note : photoselection is a commonly used technique for the production of aligned samples;
both the photoselected subset and the set of remaining molecules may be studied.; most naturally-occurring solid samples exhibit linear dichroism. it may also be produced
in the laboratory by dissolving the sample molecules in anisotropic solvents such
as nematic liquid crystals or stretched polymers. this procedure tends to produce
uniaxial samples. also crystals may be used as aligned solvents and if the sample
forms suitable crystals by itself these may be used directly. other molecular alignment
techniques include application of electric or magnetic fields.; the dichroic ratio d¿ is also a frequently used function of the wavelength. it is
defined as d¿ az ay; sometimes the reduced dichroism is used instead. it is defined as dar
az ay az 2ay az ay 3aiso withaisothe
isotropic absorbance. thus, dar is analogous to emission anisotropy and the denominator
in the equation corresponds to three times the absorbance measured in a similar but
isotropic sample.;
Origin ID : LT07415;
Automatic exact mappings (from CISMeF team)
- See also
For a uniaxial sample with sample axis Z is defined as: \[Δ A_{{l}} A_{Z} - A_{Y}\]
where AZ and AY are the absorption spectra measured with the electric vector of linearly
polarized light along and perpendicular to the sample axis, respectively. For an isotropic
sample ΔAl 0.
