This effect has been applied across the EM spectrum, where different wavelengths of light can probe a host of chemical systems.
By using light parallel and perpendicular to the orientation direction it is possible to measure how much more energy is absorbed in one dimension of the molecule relative to the other, providing information to the experimentalist.
Alternatively, the electric transition polarisation can be found to be perfectly perpendicular to the orientation of the molecule, giving rise to the following equation: This equation represents the LD signal recorded if the electric transition is polarised across the width of the molecule (i.e. perpendicular to the orientation axis), which in the case of LD is the smaller of the two investigable axes.
In addition, other types of molecule have been analysed by UV LD, including carbon nanotubes[4] and their associated ligand complexes.
This method also requires only very small amounts of analysis sample ( 20 - 40 μL) in order to generate an LD spectrum.
With biomacromolecules flow orientation is often used, other methods include stretched films, magnetic fields, and squeezed gels.
Thus LD gives information such as alignment on a surface or the binding of a small molecule to a flow-oriented macromolecule, endowing it with different functionality from other spectroscopic techniques.
[6] Fluorescence-detected linear dichroism (FDLD) is a very useful technique to the experimentalist as it combines the advantages of UV LD whilst also offering the confocal detection of the fluorescence emission.
[7] FDLD has applications in microscopy, where can be used as a means of two-dimensional surface mapping through differential polarisation spectroscopy (DPS) where the anisotropy of the scanned object allows an image to be recorded.
The intensity difference recorded between the two types of polarised light for the fluorescence reading is proportional to the UV LD signal, allowing the use of DPS to image surfaces