What type of x-rays forms the foundation of XRF analysis?

• A. Characteristic
• B. Bremsstrahlung
• C. Backscattered
• D. Auger

Answer: (A)

Element-specific fingerprints in XRF come from characteristic X-rays. When the sample is irradiated, inner-shell electrons are ejected, creating vacancies. Electrons from higher shells drop down to fill those vacancies, and the energy released as they do so is emitted as photons with energies unique to each element. These characteristic X-ray lines form the distinct peaks used to identify and quantify the elements present.

Bremsstrahlung, on the other hand, is a continuous spectrum produced by the deceleration of charged particles, which creates background rather than element-specific signals. Backscattered radiation is the primary beam that has bounced off the sample and is not the signature used for elemental identification. Auger emission is another relaxation process that involves electrons, not X-ray photons, and is not the fundamental signal relied on in standard XRF analysis.