What is "tetraoxygen"

n. (context chemistry English) an allotrope of oxygen having four atoms in each molecule instead of the normal two; only stable under very high pressures

The tetraoxygen molecule (O), also called oxozone, was first predicted in 1924 by Gilbert N. Lewis, who proposed it as an explanation for the failure of liquid oxygen to obey Curie's law. Today it seems Lewis was off, but not by much: computer simulations indicate that although there are no stable O molecules in liquid oxygen, O molecules do tend to associate in pairs with antiparallel spins, forming transient O units. In 1999, researchers thought that solid oxygen existed in its ε-phase (at pressures above 10 GPa) as O. However, in 2006, it was shown by X-ray crystallography that this stable phase known as ε oxygen or red oxygen is in fact . Nevertheless, tetraoxygen has been detected as a short-lived chemical species in mass spectrometry experiments.

Absorption bands of the O molecule e.g. at 360, 477 and 577 nm are frequently used to do aerosol inversions in atmospheric optical absorption spectroscopy. Due to the known distribution of O and therefore also O, O slant column densities can be used to retrieve aerosol profiles which can then be used again in radiative transfer models to model light paths.