expand data collection conditions datanames

[rowlesmr]

In conversation with colleagues, the recording of experimental conditions for in situ/operando data came up.

(This may be better suited for core, but I'll start here, and it can be migrated later.)

Currently, we can record the temperature, pressure, and environment (ie gas/liquid if not air) at which intensities were measured. There are many more things that can be controlled during an experiment:

• electric field (eg ferroelectrics)
• magnetic field
• voltage (batteries)
• current (batteries)
• stress (metals and fatigue cycling)
• illumination (laser pulses, etc)

Is this worth pursuing?

[briantoby]

Yes

On Sep 19, 2022, at 4:11 AM, Matthew Rowles @.**@.>> wrote:

In conversation with colleagues, the recording of experimental conditions for in situ/operando data came up.

(This may be better suited for core, but I'll start here, and it can be migrated later.)

Currently, we can record the temperature, pressure, and environment (ie gas/liquid if not air) at which intensities were measured. There are many more things that can be controlled during an experiment:

• electric field (eg ferroelectrics)
• magnetic field
• voltage (batteries)
• current (batteries)
• stress (metals and fatigue cycling)
• illumination (laser pulses, etc)

Is this worth pursuing?

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[jamesrhester]

These are definitely worth developing but most of them would be more useful in a general "environment" extension dictionary as none of them are powder-specific. Given the breadth of techniques listed you'd probably want to collect together a specialist group, have monthly meetings to hash out the contents etc. COMCIFS can provide a Github workspace here to do that if you can provide the specialist group - my colleagues at ANSTO could cover quite a few of those topics but that might be a bit too geographically non-diverse.

A further note is that a lot of these techniques require providing geometric information. There is a proto-proposal soon to be presented by the high-pressure community which would give a CIF framework for doing this, so it might be worth waiting for that.

[rowlesmr]

Roger. I was thinking to expand the available _diffrn data names.

I was also thinking that something like magnetic/electric field would also need some direction recorded as well, esp. with single xstal work.

[rowlesmr]

I've emailed a bunch of people (including ANSTO sample environments) and have had some feedback on things to record.

This is a bit of a datadump of things so far.

all data names below also have:

• _su: Standard uncertainty of _____ at which intensities were measured.
• _gt: _____ above which intensities were measured. _lt can also be used to create a range.
• _lt: _____ below which intensities were measured. _gt can also be used to create a range.
• _details: A description of special aspects of _____ during data collection.

New data names:

• _diffrn.ambient_electric_field
  • Mean electric field at which intensities were measured; volts per metre
  • Does this require a direction? with respect to laboratory, crystal plane, ...?
• _diffrn.ambient_magnetic_field
  • Mean magnetic field at which intensities were measured; ??ampere per metre or newton-metres per ampere??
  • Does this require a direction? with respect to laboratory, crystal plane, ...?
  • Is magnetic field strength or magnetic flux density the best way to record?.
• _diffrn.applied_voltage
  • Mean voltage applied to specimen while intensities were measured; volts
• _diffrn.applied_current
  • Mean current applied to specimen while intensities were measured; amperes
• _diffrn.applied_stress
  • Mean stress applied to specimen while intensities were measured; megapascals
• _diffrn.applied_strain
  • Mean strain exhibited by specimen while intensities were measured; none
• _diffrn.ambient_relative_humidity
  • Mean relative humidity at which intensities were measured; percent
• _diffrn.ambient_illumination_intensity|brilliance|flux|luminance
  • Mean photon intensity (or some other unit of illuminance) at which diffraction intensities were measured; units??
  • To be used when the illumination is designed to stimulate some structural response, not for general light illumination of a specimen for visualisation, or where illumination is a by-product, such as halogen lamp furnaces.
• _diffrn.ambient_illumination_wavelength|wavenumber|energy
  • Mean photon wavelength at which intensities were measured; units??

Questions to answer:

• what other environmental parameters would you like to capture?
• do any of these require additional information, particularly for powder vs single xstal. eg directions, gradients...
• How to deal with stimuli that are provided before actual intensity measurements that are designed to influence structure but are not actually present with the intensities are measured? Is _diffrn.crystal_treatment enough?
• are there any environmental parameters you would like to record which would need more than one value per histogram?

[jamesrhester]

This is a good starting list I think.

_lt and _gt data names are usually a bad idea unless the quantity couldn't be measured and these are needed to say something like "I know it's no more than this but otherwise no idea" e.g. if a sample would have melted above a certain temperature. Generally better to use the _su data name to indicate the accuracy of the values or variability during measurement.

Field, voltage, stress, strain would require directional information. Stress and strain are likely to need a whole separate loop or else some qualification to note that they are isotropic.

The ambient data names (not electric or magnetic) could be created without much further consultation on the assumption that they imply isotropic conditions.