Which decay emits high-energy electromagnetic photons?
Gamma emission occurs when a nucleus in excited state relaxes to lower energy by releasing electromagnetic photons without change in proton or neutron count. These photons carry energies typically from 0.1 to several MeV, possess no mass or charge, and exhibit very high penetration with low linear ionization. They often follow alpha or beta decay that leaves daughter nuclei excited. Because photons escape tissues easily, gamma emitters are externally detectable, requiring dense lead shielding and serving as valuable tracers in medical imaging and ecological field studies.
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.