Electromagnetic radiation

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  • Radiation consisting of excited photons in varying frequencies
  • Certain categories overlap; boundary between types not strict, and categories are as much from radiative source as from energy level
  • From least to most generally energetic:
    • Non-ionizing
      • Radio
      • Microwave
        • Ranges from 1.24 µeV–1.24 meV
      • Infrared
        • Ranges from 1.24 meV-1.7 eV
      • Visible light
        • Ranges from 1.7-3.1 eV
    • Ionizing
      • Ultraviolet
        • Ranges from 3.1-120 eV
      • X-ray
        • Divided into soft X-rays (~100 eV-10 keV) and hard X-rays (10+ keV)
        • Usually no more energetic than ~120 keV, but can be produced with energies upwards of 1 MeV; such are known as high-energy x-rays, or HEX-rays
        • HEX-rays distinguished from low-energy gamma radiation by source: charged particles colliding with matter
      • Gamma
        • Generally 125+ keV, but some nuclear decay detected as low as 0.08 keV
        • Low-energy gamma radiation distinguished from HEX-rays by source: produced by the nucleus of an atom, often through radioactive decay
  • General properties