Final answer:
Absorption of electromagnetic radiation can result in transitions among allowed energy levels in atoms and molecules. Examples include the absorption of X-rays by atoms and the absorption of light by transition metal complexes.
Step-by-step explanation:
Absorption of electromagnetic radiation can result in transitions among allowed energy levels in atoms and molecules. These transitions are known as electric dipole transitions and involve the absorption or emission of photons. For example, the absorption of X-rays by atoms can lead to transitions between energy levels, resulting in the emission of short wavelength X-ray photons. Similarly, the absorption of light by transition metal complexes can cause transitions between d orbitals, resulting in the absorption of photons in the visible range.