Neonhelium

Neonhelium is a hypothetical material described in theoretical discussions of noble-gas chemistry under extreme conditions. It is named by combining the chemical symbols of neon (Ne) and helium (He) to denote a potential mixed phase or diatomic complex involving both elements. Under ordinary conditions neon and helium are inert and do not form stable compounds, so Neonhelium remains speculative.

Most models treat Neonhelium as a van der Waals–bound complex, possibly existing as NeHe in transient clusters rather than as a discrete, long‑lived solid. If such a species could be stabilized, it would be expected to have extremely weak bonding, very low condensation temperatures, and spectroscopic signatures that are difficult to observe against the parent gases.

Synthetic routes would require extreme pressure and cryogenic temperatures, such as those achievable in diamond‑anvil cell experiments, combined with precise spectroscopy to identify NeHe signatures. Computational methods, including quantum‑chemical calculations, are used to estimate its binding energy and predicted spectra, but experimental confirmation has not been reported.

The concept emerged in theoretical work on noble-gas compounds; as of 2025, no confirmed observation of Neonhelium has been reported. While Neonhelium has no established practical applications, its study informs understanding of noble-gas interactions at high density and may have implications for models of planetary interiors where neon and helium coexist at extreme pressures.