An x-ray fluorescence system

An X-ray fluorescence system comprising:

• an X-ray source adapted to emit X-ray radiation that is incident on a sample;
• a controller associated with the X-ray source, the controller adapted to vary an energy of the X-ray radiation that is incident on the sample between at least a first incident radiation energy and a second incident radiation energy, the second incident radiation energy being higher than the first incident radiation energy;
• and
• an X-ray fluorescence detector to detect X-ray radiation fluoresced by the sample in response to the X-ray radiation that is incident on the sample and determine at least:
• a first fluorescence radiation intensity of X-ray radiation fluoresced by the sample in response to the X-ray radiation incident on the sample at the first incident energy;
• and
• a second fluorescence radiation intensity of X-ray fluorescence radiation fluoresced by the sample in response to the X-ray radiation incident on the sample at the second incident energy;
• and
• a processor to determine a particle size correction factor based on the first fluorescence radiation intensity and the second fluorescence radiation intensity.