Discussion Group B2

Discussion Leaders

• Adrian Rennie

Discsussion Notes

We started by asking what people would like from 'round-robin', 'reference' and 'calibration' samples.

As regards calibration there is need to verify:

• momentum transfer
• intensity
• resolution

The sample should be stable, non-toxic and should be available in sufficient quantity to be spread widely. It is desirable that samples are easy to measure: eliminate user errors. Scattering should be sufficiently strong that measurement times are reasonably short.

It was noted that no single sample might be ideal for all of these purposes across a range of instruments for both X-ray and neutron scattering. Some of the difficulties with presently available samples were discussed.

Several ideas for samples were discussed and it was recognized that some of these would need initial tests as they had not been tested. These were also presented and augmented in the general discussion.

Some ideas that were mentioned are:

• copolymers that show a correlation peak (e.g. styrene/polyisobutylene)
• microfabricated samples such as gratings
• deuterated sodium dodecyl sulfate crystals
• polymers filled with silica or other particles
• Irradiated light metals with pores
• metal alloys with precipitates - iron or nickel (e.g. WASP alloys) based
• patterned gold foils: Nano fabricated materials,e-beam fabricated samples
• anodized aluminium foils
• photo patterned polymers
• lithographically-prepared samples
• crystallites in glasses (quantum dots)

It was noted that some of these ideas for samples do not represent readily available samples and that it would be necessary to make tests or engage in preparatory work. Participants were encouraged to try these and then engage further with others for comparative tests.

A further list of samples that are now available and could be circulated to further laboratories was drawn up

• Silver behenate from a single batch
• Porous carbon
• polystyrene latex particles (from previous round robin)

to be continued