The spectral energy distribution of the microwave background radiation found in the universe is that of a perfectly absorbing body (blackbody) radiating at 2.70 Kelvin.

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Spectral interference occurs when spectral lines overlap. Inductively-coupled plasma mass spectrometry has more spectral interference as its higher energy allows more electron transitions.

When the electrons absorb energy from a source, such as heat, they move to an excited state (farther from the atoms nucleus). They then release the energy in the form of light which produces the observed spectral lines of color. Once the energy is released, the electrons move back to a lower energy level (ground state).