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Proposal to define data names for atomic analysis information

  • To: Distribution list of the IUCr COMCIFS Core Dictionary Maintenance Group<coredmg@iucr.org>
  • Subject: Proposal to define data names for atomic analysis information
  • From: James H via coreDMG <coredmg@iucr.org>
  • Date: Tue, 4 Oct 2022 12:43:41 +1100
  • Cc: James H <jamesrhester@gmail.com>
Dear Core CIF dictionary maintenance group:

A proposal has been developed by some powder people to include results of sample analysis for atomic content in CIF files. It seems to me that this is more general than just powder, so I have transferred to proposal to the CIF core dictionary issues list. Please read through https://github.com/COMCIFS/cif_core/issues/304 and add your comments there or here. For reference, the final comment on that issue, which gives the flavour of the proposal, is reproduced below.

best wishes,
James.
=================================

Given the desire to allow general details of techniques to be included, we will need one or more separate categories. One alternative is to bundle all details of techniques into a general purpose category, in the example below it is ATOM_ANALYTICAL_TECHNIQUE

Here is an example of how this would appear in the CIF file (adapted from above):

data_block1
loop_
_atom_analytical.id
_atom_analytical.atom_type
_atom_analytical.chemical_species
_atom_analytical.analytical_mass_percent
_atom_analytical.chemical_species_mass_percent
_atom_analytical.technique_id  #<- refers to an _atom_analytical_technique.id
1  Si  SiO2   ?     22.7  XRF
2  Al  Al2O3  ?     27.4  XRF
3  Ti  TiO2   ?      2.7  XRF
4  Si  .      10.5  .     ICP
5  Si  Si     11.7  11.7  EDS

loop_
_atom_analytical_technique.id        #<- this could be a run id if more than one performed
_atom_analytical_technique.type    #XRF/ICP/EDS etc.
_atom_analytical_technique.special_details
XRF   XRF
;
The loss on ignition at 1000 °C was 12.4 wt%
;

#...

The other alternative, and the one most conducive to expansion in the future, is to define categories for each analytical technique. These can remain largely empty until others want to fill them in. So the above would become:

loop_
_atom_analytical.id
_atom_analytical.atom_type
_atom_analytical.chemical_species
_atom_analytical.analytical_mass_percent
_atom_analytical.chemical_species_mass_percent
_atom_analytical.technique_type
1  Si  SiO2   ?     22.7  XRF
2  Al  Al2O3  ?     27.4  XRF
3  Ti  TiO2   ?      2.7  XRF
4  Si  .      10.5  .     ICP
5  Si  Si     11.7  11.7  EDS

_atom_analytical_XRF.mass_loss_percent    12.4
_atom_analytical_XRF.ignition_temperature   1000

Of these I strongly prefer the second as it ensures that the minimum amount of information is hidden in machine-opaque text.

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