Homonuklearne

Homonuklearne is an adjective used in physics and chemistry to describe systems in which the participating nuclei are identical or belong to the same nuclear species. The term is most often applied in two areas: chemistry and spectroscopy, and nuclear magnetic resonance.

In chemistry, homonuklearne commonly refers to homonuclear diatomic molecules—molecules composed of two identical atoms. Examples include H2, N2, O2, F2, and Cl2. Because these molecules have identical nuclei, they typically possess no permanent electric dipole moment, a consequence of symmetry. This leads to infrared inactivity for many fundamental vibrational transitions, while Raman spectroscopy can still detect their vibrational modes. Their rotational spectra are also governed by symmetry considerations.

In spectroscopy and related fields, homonuklearne also describes interactions between identical nuclear species. For example, in proton NMR, 1H–1H couplings produce characteristic multiplet structures, and specialized decoupling schemes target these homonuclear couplings. In broader physics contexts, the term can describe nuclei sharing the same isotopic identity or similar spin environments, affecting hyperfine interactions and energy-level diagrams.

The concept is contrasted with heteronuklearne (heteronuclear) systems, which contain different nuclear species, such as hydrogen and carbon, and exhibit different dipole moments and coupling patterns. The term derives from the prefix homo- meaning “same” and nucleus, reflecting identical nuclear components within the system. See also: heteronuclear, diatomic molecules, NMR coupling.