Before submitting a sample to the scXRD service, you will need to examine your crystals and identify if there are crystals that appear to be suitable for diffraction. This page assumes that crystals have been grown in a sample vial, but these instructions can be adapted for other containers used to grow crystals.

Visual appearance

The vial should be inspected to see if crystals have visibly grown.

Crystal dimensions

Crystals do not need to be large. A good single crystal used for diffraction is typically around 0.2 × 0.2 × 0.2 mm, and it is certainly possible to acquire good data from crystals which are much smaller than this.

Viewing on a microscope

Crystals should be examined under a microscope fitted with a polariser to properly determine if they are likely to be suitable for X-ray diffraction.

Appearance

Crystals should have a regular form, with clearly defined straight edges.

• Clear / transparent in appearance

• Smooth and flat faces

• Regular angles between sides and faces

Interaction with polarised light

Crystals should change colour in a uniform manner when the polariser is adjusted. The colour observed is not important, but the whole of the crystal should change colour at the same time. For longer crystals, you might find that there are two or more sections of different colours on polarisation. It may well be possible to cut the crystal to use only a single crystal section.

Gallery of examples

The gallery of microscope images provides examples of crystals viewed under a microscope to identify if the crystals would be suitable for diffraction. Each picture is accompanied by an indication if the samples would have been suitable or not.