How does an X-Ray Fluorescence (XRF) Analyzer work?

• A. It exposes a painted surface to radiation emitted from a sealed source inside the instrument (either Cobalt 57 or Cadmium 109)
• B. It uses gamma rays to strike the protective coating
• C. It analyzes surface color to determine lead content
• D. It relies on ambient light to excite the sample

Answer: (A)

X-ray fluorescence works by using X-rays from a sealed radioactive source inside the instrument to irradiate the surface. Those X-rays knock inner-shell electrons from atoms in the paint, and when electrons from higher shells fill the vacancies, the atoms emit their own characteristic X-rays. The detector then measures the energies and intensities of these emitted X-rays, identifying and quantifying elements like lead. This explanation matches the described setup of a sealed source inside the device producing the excitation radiation. The other options don’t fit because XRF relies on X-rays to excite atoms (not gamma rays), it detects elemental signatures rather than color, and it does not depend on ambient light.