Sample Types

Powders

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Powdered samples are commonly prepared as pellets or powders sealed in kapton or scotch tape. These can be fixed to our room temperature holders or cryostat sticks.
Our sample holders are made out of perspex or aluminium.

Films

Films can also be simply fixed to our sample holders and loaded in either the room temperature or cryostat environments.

Liquids

We have liquid sample holders that can be used either in the room temperature or cryostat environments. Generally, we freeze liquid samples to avoid gas / bubble formation during exposure, which can distort spectra.

Coin cell batteries

Coin cells can be mounted in our room temperature environment.

Other sample types

We can accommodate a range of sample environments, contact us to find out more.

Sample preparation

If you can prepare a sample for transmission analysis, this is preferred.

Transmission

The XAFSMass program can be used to estimate how much sample you need to produce an ideal sample for transmission measurements. Here is some information about sample preparation and a guide to using XAFSMass.

Total thickness should be between 1-2 absorption lengths (keep below <2-3 absorption lengths) including substrates to minimize thickness effects.

The element of interest must be concentrated enough to get a significant edge jump (e.g. >0.3 absorption lengths).

To prepare a good transmission sample, you must calculate the expected absorption for each sample, using XAFSMass or a similar calculator, and dilute accordingly with boron nitride or similar (e.g. cellulose).

If your calculations show that it is not possible to prepare a good transmission sample, consider fluorescence as described below.

Ensure particles are ground small and mixed homogenously - avoid pinhole effects.

Fluorescence

If some of your samples are not suitable for measuring in transmission (i.e. dilute concentration), it is advisable to analyse all of your samples by fluorescence measurements.

Your sample should be prepared either as 1) a thin concentrated sample, or 2) a thick dilute sample.

Powder samples:

Particle size must be small compared to absorption lengths of particles.

Dilute your samples as necessary to approximately 1000 ppm of the element of interest (avoid exceeding about 2000 ppm). (this is just a rough estimate and depends on the element weight)

For sample dilution, we commonly use cellulose (note boron nitride will diffract so is not recommended for fluorescence measurements).

Homogeneity is very important so take your time when diluting and mixing samples.

Film samples:

Again, homogeneity is a priority, and a flat surface is preferred.