Rationale
Electromagnetic radiation interacts with matter in different ways in different parts of the spectrum. The types of interaction can be so different that it seems to be justified to refer to different types of radiation. At the same time, there is a continuum containing all these "different kinds" of electromagnetic radiation. Thus we refer to a spectrum, but divide it up based on the different interactions with matter.
| Region of the spectrum | Main interactions with matter |
|---|---|
| Radio | Collective oscillation of charge carriers in bulk material (plasma oscillation). An example would be the oscillation of the electrons in an antenna. |
| Microwave through far infrared | Plasma oscillation, molecular rotation |
| Near infrared | Molecular vibration, plasma oscillation (in metals only) |
| Visible | Molecular electron excitation (including pigment molecules found in the human retina), plasma oscillations (in metals only) |
| Ultraviolet | Excitation of molecular and atomic valence electrons, including ejection of the electrons (photoelectric effect) |
| X-rays | Excitation and ejection of core atomic electrons, Compton scattering (for low atomic numbers) |
| Gamma rays | Energetic ejection of core electrons in heavy elements, Compton scattering (for all atomic numbers), excitation of atomic nuclei, including dissociation of nuclei |
| High-energy gamma rays | Creation of particle-antiparticle pairs. At very high energies a single photon can create a shower of high-energy particles and antiparticles upon interaction with matter. |
Read more about this topic: Electromagnetic Spectrum