Data Item _diffrn_radiation.polarizn_Stokes_Q
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General 
- Item name
- _diffrn_radiation.polarizn_Stokes_Q
- Category name
- diffrn_radiation
- Attribute name
- polarizn_Stokes_Q
- Required in PDB entries
- no
- Used in currrent PDB entries
- No
Item Description
(Ip-In)*cos(2*theta), where where Ip is the intensity
(amplitude squared) of the electric vector in the plane of
polarization, In is the intensity (amplitude squared) of
the electric vector in the plane of the normal to the
plane of polarization, and theta is the angle as viewed
from the specimen, between the normal to the polarization
plane and the laboratory Y axis as defined in the
AXIS category.
This is an average or other representative sample of the
scan.
This is the second of the Stokes polarization parameters,
I, Q, U, V (also known as I, M, C, S). See
H. H. Berry, G. Gabrielse, A. E. Livingston (1977),
"Measurement of the Stokes parameters of Light",
Applied Optics, 16:12, 3200 -- 3205.
If the absolute intensity is not known, the value 1.
is assumed for I, and all 4 Stokes parameters are
dimensionless. When the absolute intensity is known,
all 4 Stokes parameters are in units of Watts per
square meter.
Data Type 
- Data type code
- float
- Data type detail
- float item types are the subset of numbers that are the floating point numbers.
- Primitive data type code
- numb
- Regular expression
- -?(([0-9]+)[.]?|([0-9]*[.][0-9]+))([(][0-9]+[)])?([eE][+-]?[0-9]+)?