X-ray fluorescence system and x-ray source with electrically insulative target material

A system comprising:

• a stage configured to support a sample comprising at least first and second atomic elements, the first atomic element having a first characteristic x-ray line with a first energy, the second atomic element having a second characteristic x-ray line with a second energy, the second energy greater than the first energy, the first energy and the second energy lower than 8 keV and separated from one another by less than 1 keV;
• an x-ray source comprising at least one target material configured to produce x-rays having a third energy between the first and second energies;
• at least one x-ray optic configured to receive and focus at least some of the x-rays from the x-ray source as an x-ray beam to illuminate the sample, the x-ray beam having a spot size at the sample in a range of 1 micron to 25 microns, at least 70% of the x-ray beam having x-ray energies that are below the second energy;
• and
• at least one x-ray detector configured to detect fluorescence x-rays produced by the sample in response to being irradiated by the x-ray beam.