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Powder dictionary (pdCIF) version 1.0.1

Category PD_INSTR

Name:
'_pd_instr_[pd]'

Definition:

   This section contains information relevant to the instrument
   used for the diffraction measurement. For most laboratories,
   very little of this information will change, so a standard file
   may be prepared and included with each data set.

   Note that several definitions in the core CIF dictionary
   are relevant here. For example, use:
     _diffrn_radiation_wavelength for the source wavelength,
     _diffrn_radiation_type for the X-ray wavelength type,
     _diffrn_source for the radiation source,
     _diffrn_radiation_polarisn_ratio for the source polarization,
     _diffrn_radiation_probe for the radiation type.
   For data sets measured with partially monochromatized radiation,
   for example, where both K\a~1~ and K\a~2~ are present, it is
   important that all wavelengths present are included in a
   loop_ using _diffrn_radiation_wavelength to define the 
   wavelength and _diffrn_radiation_wavelength_wt to define the 
   relative intensity of that wavelength. It is required that 
   _diffrn_radiation_wavelength_id also be present in the 
   wavelength loop. It may also be useful to
   create a "dummy" ID to use for labelling
   peaks/reflections where the K\a~1~ and K\a~2~ wavelengths are
   not resolved. Set _diffrn_radiation_wavelength_wt to be 0 for
   such a dummy ID.

   In the _pd_instr_ definitions, the term monochromator refers
   to a primary beam (pre-specimen) monochromator and the term
   analyser refers to post-diffraction (post-specimen)
   monochromator.  The analyser may be fixed for specific
   wavelength or may be capable of being scanned.

   For multiple-detector instruments it may be necessary to loop the
   *_anal/detc or *_spec/detc values (for  _pd_instr_dist_,
   _pd_instr_divg_, _pd_instr_slit_ and  _pd_instr_soller_) with
   the detector IDs (_pd_calib_detector_id).

   It is strongly recommended that the core dictionary term
   _diffrn_radiation_probe (specifying the nature of the radiation
   used) is employed for all data sets.

Example:

Example 1.
 
    _pd_instr_slit_eq_src/spec       1.
    _pd_instr_slit_eq_anal/detc      0.2

    _pd_instr_geometry              Bragg-Brentano
    _pd_instr_monochr_post_spec     'graphite (0001)'
    _pd_instr_cons_illum_flag       no



Type: null

Category: category_overview