X-ray

X-rays (aka Röntgen rays, after their discoverer Wilhelm Conrad Röntgen) are an ionizing type of electromagnetic radiation in the frequency range of 3×10¹⁶Hz to 3 × 10¹⁹Hz. They can be divided into the more energetic hard x-rays (3×10¹⁸Hz to 3 × 10¹⁹Hz) adjacent to gamma rays, and into soft x-rays (3×10¹⁶Hz to 3 × 10¹⁸Hz), adjacent to ultraviolet light. They are widely used for structural investigations in all parts of materials science, though care has to be exerted for uses on living tissue, since ionizing radiation can cause cell damage.