Capillary Samples

Where possible, samples should be loaded in capillaries for data collection. This section describes how this can be done.

1. What size capillaries should I use?
It is normally recommended that users use 0.3 mm low X-ray absorption glass capillaries; the angular resolution is optimised by using as small a diameter as possible. Capillary sizes >0.5 mm are not recommended.

2. How much sample do I need?
For ease of experiment set-up, the length of sample needed in the capillary is around 15-20 mm (or more). However, it is not necessary to fill all of this, it is possible to work with as little as 3-5 mm.  To seal the capillary break the funnel, and any excess capillary, off and seal it close to the sample, i.e. not more than 10 mm away.

3. What type of capillaries should I use?
Most experiments will use 'special glass' capillaries, but high temperature experiments will require 'quartz' capillaries (these can be used up to 1370 K).

4. Where can I purchase suitable capillaries?
Capillaries can be purchased from Hampton Research or Charles Supper
http://hamptonresearch.com/menus.aspx?id=3&sid=110
http://www.charles-supper.com/en/page/category.cfm?idCategory=13

5. How do I pack sample in capillaries?
Hints for loading capillaries are as follows:

• The sample should be finely and uniformly ground
• Load only the smallest amount (<1 mm deep) of material into the capillary funnel at any one time - otherwise the sample becomes stuck pretty early on in the capillary.
• Vibration is the key to moving the sample down and a good light source behind the capillary is needed to see whether the sample has moved down the capillary and/or is coating the sides of the capillary.
• Vibration can be achieved by running a small, fine file across the capillary (while holding the capillary lightly between your fingers); or by 'dropping'/tapping the capillary on a hard surface, e.g. use a narrow tube of at least 15 cm length which the whole capillary will slide through and drop the capillary into the top and let it land on a bench top (this is a repetitive process); or by standing the capillary upright in a beaker or similar container, and placing this in a sonicator; or finally, if you have a vibrating hand held tool you can hold it to the capillary and get the sample to shuffle down.

If it has not been possible to load sample in a capillary, it may be appropriate in certain situations, to adhere the sample to the outer wall of the capillary using Vaseline.

Furnace Samples

Hints on the preparation of samples for furnace experiments are provided by Anton Paar and are available here.  Additional information regarding the reactivity of samples with platinum is available here; this information should be read carefully, well in advance of the proposed experiment.