.. auto-generated by script ../../../../utils/nxdl2rst.py from the NXDL source ../../../../base_classes/NXcrystal.nxdl.xml .. index:: ! NXcrystal (base class) ! crystal (base class) see: crystal (base class); NXcrystal .. _NXcrystal: ========= NXcrystal ========= **Status**: base class, extends :ref:`NXobject`, version 1.0 **Description**: Template of a crystal monochromator or analyzer. Permits double bent monochromator comprised of multiple segments with anisotropic Gaussian mosaic. If curvatures are set to zero or are absent, array is considered to be flat. Scattering vector is perpendicular to surface. Crystal is oriented parallel to beam incident on crystal before rotation, and lies in vertical plane. **Symbols**: These symbols will be used below to coordinate dimensions with the same lengths. **n_comp**: number of different unit cells to be described **i**: number of wavelengths **Groups cited**: :ref:`NXdata`, :ref:`NXgeometry`, :ref:`NXlog`, :ref:`NXshape` .. index:: NXgeometry (base class); used in base class, NXlog (base class); used in base class, NXdata (base class); used in base class, NXshape (base class); used in base class **Structure**: .. index:: usage (data field) **usage**: :ref:`NX_CHAR ` How this crystal is used. Choices are in the list. Any of these values: * ``Bragg``: reflection geometry * ``Laue``: The chemical formula specified using CIF conventions. Abbreviated version of CIF standard: * Only recognized element symbols may be used. * Each element symbol is followed by a 'count' number. A count of '1' may be omitted. * A space or parenthesis must separate each cluster of (element symbol + count). * Where a group of elements is enclosed in parentheses, the multiplier for the group must follow the closing parentheses. That is, all element and group multipliers are assumed to be printed as subscripted numbers. * Unless the elements are ordered in a manner that corresponds to their chemical structure, the order of the elements within any group or moiety depends on whether or not carbon is present. * If carbon is present, the order should be: C, then H, then the other elements in alphabetical order of their symbol. If carbon is not present, the elements are listed purely in alphabetic order of their symbol. This is the *Hill* system used by Chemical Abstracts. See, for example: http://www.iucr.org/__data/iucr/cif/standard/cifstd15.html, http://www.cas.org/training/stneasytips/subinforformula1.html, or http://www.indiana.edu/~cheminfo/courses/471cnfs.html. .. index:: type (data field) **type**: :ref:`NX_CHAR ` Type or material of monochromating substance. Chemical formula can be specified separately. Use the "reflection" field to indicate the (hkl) orientation. Use the "d_spacing" field to record the lattice plane spacing. This field was changed (2010-11-17) from an enumeration to a string since common usage showed a wider variety of use than a simple list. These are the items in the list at the time of the change: PG (Highly Oriented Pyrolytic Graphite) | Ge | Si | Cu | Fe3Si | CoFe | Cu2MnAl (Heusler) | Multilayer | Diamond. .. index:: chemical_formula (data field) **chemical_formula**: :ref:`NX_CHAR ` The chemical formula specified using CIF conventions. Abbreviated version of CIF standard: * Only recognized element symbols may be used. * Each element symbol is followed by a 'count' number. A count of '1' may be omitted. * A space or parenthesis must separate each cluster of (element symbol + count). * Where a group of elements is enclosed in parentheses, the multiplier for the group must follow the closing parentheses. That is, all element and group multipliers are assumed to be printed as subscripted numbers. * Unless the elements are ordered in a manner that corresponds to their chemical structure, the order of the elements within any group or moiety depends on whether or not carbon is present. * If carbon is present, the order should be: C, then H, then the other elements in alphabetical order of their symbol. If carbon is not present, the elements are listed purely in alphabetic order of their symbol. * This is the *Hill* system used by Chemical Abstracts. .. index:: order_no (data field) **order_no**: :ref:`NX_INT ` A number which describes if this is the first, second,.. :math:`n^{th}` crystal in a multi crystal monochromator .. index:: cut_angle (data field) **cut_angle**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_ANGLE `} Cut angle of reflecting Bragg plane and plane of crystal surface .. index:: space_group (data field) **space_group**: :ref:`NX_CHAR ` Space group of crystal structure .. index:: unit_cell (data field) **unit_cell[n_comp, 6]**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_LENGTH `} Unit cell parameters (lengths and angles) .. index:: unit_cell_a (data field) **unit_cell_a**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_LENGTH `} Unit cell lattice parameter: length of side a .. index:: unit_cell_b (data field) **unit_cell_b**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_LENGTH `} Unit cell lattice parameter: length of side b .. index:: unit_cell_c (data field) **unit_cell_c**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_LENGTH `} Unit cell lattice parameter: length of side c .. index:: unit_cell_alpha (data field) **unit_cell_alpha**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_ANGLE `} Unit cell lattice parameter: angle alpha .. index:: unit_cell_beta (data field) **unit_cell_beta**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_ANGLE `} Unit cell lattice parameter: angle beta .. index:: unit_cell_gamma (data field) **unit_cell_gamma**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_ANGLE `} Unit cell lattice parameter: angle gamma .. index:: unit_cell_volume (data field) **unit_cell_volume**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_VOLUME `} Volume of the unit cell .. index:: orientation_matrix (data field) **orientation_matrix[3, 3]**: :ref:`NX_FLOAT ` Orientation matrix of single crystal sample using Busing-Levy convention .. index:: wavelength (data field) **wavelength[i]**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_WAVELENGTH `} Optimum diffracted wavelength .. index:: d_spacing (data field) **d_spacing**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_LENGTH `} spacing between crystal planes of the reflection .. index:: scattering_vector (data field) **scattering_vector**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_WAVENUMBER `} Scattering vector, Q, of nominal reflection .. index:: reflection (data field) **reflection[3]**: :ref:`NX_INT ` {units=\ :ref:`NX_UNITLESS `} Miller indices (hkl) values of nominal reflection .. index:: thickness (data field) **thickness**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_LENGTH `} Thickness of the crystal. (Required for Laue orientations - see "usage" field) .. index:: density (data field) **density**: :ref:`NX_NUMBER ` {units=\ :ref:`NX_MASS_DENSITY `} mass density of the crystal .. index:: segment_width (data field) **segment_width**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_LENGTH `} Horizontal width of individual segment .. index:: segment_height (data field) **segment_height**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_LENGTH `} Vertical height of individual segment .. index:: segment_thickness (data field) **segment_thickness**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_LENGTH `} Thickness of individual segment .. index:: segment_gap (data field) **segment_gap**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_LENGTH `} Typical gap between adjacent segments .. index:: segment_columns (data field) **segment_columns**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_LENGTH `} number of segment columns in horizontal direction .. index:: segment_rows (data field) **segment_rows**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_LENGTH `} number of segment rows in vertical direction .. index:: mosaic_horizontal (data field) **mosaic_horizontal**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_ANGLE `} horizontal mosaic Full Width Half Maximum .. index:: mosaic_vertical (data field) **mosaic_vertical**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_ANGLE `} vertical mosaic Full Width Half Maximum .. index:: curvature_horizontal (data field) **curvature_horizontal**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_ANGLE `} Horizontal curvature of focusing crystal .. index:: curvature_vertical (data field) **curvature_vertical**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_ANGLE `} Vertical curvature of focusing crystal .. index:: is_cylindrical (data field) **is_cylindrical**: :ref:`NX_BOOLEAN ` Is this crystal bent cylindrically? .. index:: cylindrical_orientation_angle (data field) **cylindrical_orientation_angle**: :ref:`NX_NUMBER ` {units=\ :ref:`NX_ANGLE `} If cylindrical: cylinder orientation angle .. index:: polar_angle (data field) **polar_angle[i]**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_ANGLE `} Polar (scattering) angle at which crystal assembly is positioned. Note: some instrument geometries call this term 2theta. .. index:: azimuthal_angle (data field) **azimuthal_angle[i]**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_ANGLE `} Azimuthal angle at which crystal assembly is positioned .. index:: bragg_angle (data field) **bragg_angle[i]**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_ANGLE `} Bragg angle of nominal reflection .. index:: temperature (data field) **temperature**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_TEMPERATURE `} average/nominal crystal temperature .. index:: temperature_coefficient (data field) **temperature_coefficient**: :ref:`NX_FLOAT ` {units=\ :ref:`NX_ANY `} how lattice parameter changes with temperature **(geometry)**: :ref:`NXgeometry` Position of crystal **temperature_log**: :ref:`NXlog` log file of crystal temperature **reflectivity**: :ref:`NXdata` crystal reflectivity versus wavelength **transmission**: :ref:`NXdata` crystal transmission versus wavelength **shape**: :ref:`NXshape` A NXshape group describing the shape of the crystal arrangement **Source**: Automatically generated from https://github.com/nexusformat/definitions/blob/master/base_classes/NXcrystal.nxdl.xml