Tetraoxygen

History

Tetraoxygen 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.{{cite journal | hdl-access = free

Structure

Theoretical calculations have predicted the existence of metastable O4 molecules with two different shapes: a "puckered" square like cyclobutane or S4,{{cite journal

In 2001, a team at the University of Rome La Sapienza conducted a neutralization-reionization mass spectrometry experiment to investigate the structure of free O4 molecules. Their results did not agree with either of the two proposed molecular structures, but they did agree with a complex between two O2 molecules, one in the ground state and the other in a specific excited state.

A chain structure is theoretically possible, but attempts at advanced computational analysis found that it rearranged to the D2d structure.

Atmospheric occurrence

In atmospheric sciences, O4 usually refers to the collision-induced complex arising from interactions between two O2 molecules. Also called O2-O2 dimers, these unstable dimers exhibit distinct collision-induced absorption (CIA) bands in the UV and visible ranges. Because molecular oxygen is well-mixed and the distribution is well known, the concentration of O2-O2 dimers is predictable and primarily dependent on air density. Since clouds change how light passes through the atmosphere, the strength of the O2-O2 absorption can be used to detect their presence and height. Therefore, satellite measurements of spectral radiance within the O2-O2 absorption bands can be used to calculate cloud properties such as cloud-top pressure and cloud fraction globally. The same absorption features, including bands at 360, 477 and 577 nm, are used to derive aerosol profiles in atmospheric optical spectroscopy, where the predictable distribution of O2 provides useful constraint in aerosol inversion techniques and radiative transfer models.

Potential use

Tetraoxygen has been speculated as an alternative to traditional liquid oxygen in rocket propulsion. Its higher density—approximately twice that of liquid oxygen—could allow for smaller oxidizer tanks, lowering overall vehicle mass and increasing payload capacity.

References

de:Allotrope Formen von Sauerstoff#Tetrasauerstoff

References

1. (1989). "Ab initio study of bonding trends in the series BO_3³⁻, CO_3²⁻, NO_3⁻ and O₄(D_3h)". Chemical Physics Letters.
2. Jubert,A.H.; E.L.Varetti (1986). "On the possible existence of the O₄ molecule with D_3h symmetry". Anales de Química (Spain)'''82''':227-230.
3. (2015). "Information entropy of oxygen allotropes. A still open discussion about the closed form of ozone". Computational and Theoretical Chemistry.
4. (2002). "UV-visible observations of atmospheric O4 absorptions using direct moonlight and zenith-scattered sunlight for clear-sky and cloudy sky conditions". Journal of Geophysical Research: Atmospheres.
5. (2004-03-16). "Cloud pressure retrieval using the O 2 -O 2 absorption band at 477 nm". Journal of Geophysical Research: Atmospheres.
6. (2021-01-05). "A Fast Retrieval of Cloud Parameters Using a Triplet of Wavelengths of Oxygen Dimer Band around 477 nm". Remote Sensing.
7. Friess, U. and Monks, P. S. and Remedios, J. J. and Wagner, T. and Platt, U.. (2005). "MAX-DOAS O4 measurements: A new technique to derive information on atmospheric aerosols - Retrieval of aerosol properties". Journal of Geophysical Research.
8. "Tetraoxygen".