Bilbao Crystallographic Server Help

Polarization Selection Rules

Back scattering geometry

ki = -ks ki ⊥ Ei and ks ⊥ Es

Right angle scattering geometry

ki ⊥ Ei ks ⊥ Es

Input of the program

• The type of process





• The point group

One can select the point group directly from a menu or one can introduce the space group number.





• Orientation (Optional)

One can introduce the orientation given the Euler angles:

Output of the program

• Information about the tensor:

The program shows the information about the tensors. In the case it is introduced an orientation it also gives the tensor in the new orientation and the relation between the initial and transformed parameters.

• Polarization selection rules:

One can find two tables with the selection rules for back and right angle scattering geometries.

• Intensity:

It is given the general expresion for the intensity for the different directions.

Examples

• Raman Tensors

In the input of the program it is selected the Raman process and the point group C_4v (4mm). The orientation in this program is optional, in this case it is not going to introduce it.

One all the parameters are introduced, click on the button Continue and the program will calculate the polarization selection rules. In the first part of the output one can find the information about the Raman tensors:



After this one can find the polarization selection rules, the first table is related to the back scattering geometry:



In the next table one can find the selection rules for right angle scattering geometry:



One can click over one of the directions of boths tables and obtain more information about the Porto notation and a explanation about why is(are) predected this(those) mode(s):



Finally, at the end of the page one can find the link to the information about the intensities:



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• Hyper-Raman Tensors

In the input of the program it is selected the option Hyper-Raman process and it has been introduced the space group number Fm-3m (No. 225). With this example one wants to calculate the polarization selection rules for this space group in a different orientation:

θ = 90;       φ = 0;       Ψ= 0

Firstly, one is going to find the information about the Hyper-Raman tensors:



As is shown there are given the original tensor and the transformed one, there are also the relation between the parameters of the transformed and untransformed tensors. After this, one can find the polarization selection rules for both geometries. The first table is related with the back scattering geometry and the second one with the right angle scattering geometry. The table above is the one with the selection rules for back scattering geometry:



One can click over one of the directions of boths tables and obtain more information about the Porto notation and a explanation about why is(are) predected this(those) mode(s):



Finally, at the end of the page one can find a link to the information about the intensities:



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