The tetraoxygen molecule (O
4), also called oxozone, is an
allotrope
Allotropy or allotropism () is the property of some chemical elements to exist in two or more different forms, in the same physical state, known as allotropes of the elements. Allotropes are different structural modifications of an element: the ...
of
oxygen
Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
consisting of four oxygen atoms.
History
Tetraoxygen was first predicted in 1924 by
Gilbert N. Lewis
Gilbert Newton Lewis (October 23 or October 25, 1875 – March 23, 1946) was an American physical chemist and a dean of the college of chemistry at University of California, Berkeley. Lewis was best known for his discovery of the covalent bon ...
, who proposed it as an explanation for the failure of
liquid oxygen
Liquid oxygen, sometimes abbreviated as LOX or LOXygen, is a clear cyan liquid form of dioxygen . It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an application which is ongoing.
Physical ...
to obey
Curie's law
For many paramagnetic materials, the magnetization of the material is directly proportional to an applied magnetic field, for sufficiently high temperatures and small fields. However, if the material is heated, this proportionality is reduced. Fo ...
. Though not entirely inaccurate, computer simulations indicate that although there are no stable O
4 molecules in liquid oxygen, O
2 molecules do tend to associate in pairs with antiparallel
spins, forming transient O
4 units. In 1999, researchers thought that
solid oxygen in its ε-phase, also known as red oxygen, (at pressures above 10
GPa
Grading in education is the application of standardized measurements to evaluate different levels of student achievement in a course. Grades can be expressed as letters (usually A to F), as a range (for example, 1 to 6), percentages, or as num ...
) was O
4.
However, in 2006, it was shown by
X-ray crystallography
X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...
that this stable
phase
Phase or phases may refer to:
Science
*State of matter, or phase, one of the distinct forms in which matter can exist
*Phase (matter), a region of space throughout which all physical properties are essentially uniform
*Phase space, a mathematica ...
is in fact
octaoxygen (). Nevertheless, positively charged tetraoxygen has been detected as a short-lived
chemical species
Chemical species are a specific form of chemical substance or chemically identical molecular entities that have the same molecular energy level at a specified timescale. These entities are classified through bonding types and relative abundance of ...
in
mass spectrometry
Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a ''mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used ...
experiments.
[
]
Structure
Theoretical calculations have predicted the existence of
metastable
In chemistry and physics, metastability is an intermediate energetic state within a dynamical system other than the system's state of least energy.
A ball resting in a hollow on a slope is a simple example of metastability. If the ball is onl ...
O
4 molecules with two different shapes: a "puckered" square like
cyclobutane
Cyclobutane is a cycloalkane and organic compound with the formula (CH2)4. Cyclobutane is a colourless gas and is commercially available as a liquefied gas. Derivatives of cyclobutane are called cyclobutanes. Cyclobutane itself is of no commerc ...
or
S4, and a "pinwheel" with three oxygen atoms surrounding a central one in a
trigonal planar formation similar to
boron trifluoride
Boron trifluoride is the inorganic compound with the formula . This pungent, colourless, and toxic gas forms white fumes in moist air. It is a useful Lewis acid and a versatile building block for other boron compounds.
Structure and bonding
The g ...
or
sulfur trioxide
Sulfur trioxide (alternative spelling sulphur trioxide) is the chemical compound with the formula SO3. It has been described as "unquestionably the most conomicallyimportant sulfur oxide". It is prepared on an industrial scale as a precursor to ...
. It was previously pointed out that the "pinwheel" O
4 molecule should be the natural continuation of the
isoelectronic
Isoelectronicity is a phenomenon observed when two or more molecules have the same structure (positions and connectivities among atoms) and the same electronic configurations, but differ by what specific elements are at certain locations in th ...
series
,
,
, and analogous to
SO3; that observation served as the basis for the mentioned theoretical calculations.
In 2001, a team at the
University of Rome La Sapienza
The Sapienza University of Rome (), formally the Università degli Studi di Roma "La Sapienza", abbreviated simply as Sapienza ('Wisdom'), is a Public university, public research university located in Rome, Italy. It was founded in 1303 and is ...
conducted a
neutralization-reionization mass spectrometry experiment to investigate the structure of free O
4 molecules.
Their results did not agree with either of the two proposed molecular structures, but they did agree with a
complex
Complex commonly refers to:
* Complexity, the behaviour of a system whose components interact in multiple ways so possible interactions are difficult to describe
** Complex system, a system composed of many components which may interact with each ...
between two O
2 molecules, one in the
ground state
The ground state of a quantum-mechanical system is its stationary state of lowest energy; the energy of the ground state is known as the zero-point energy of the system. An excited state is any state with energy greater than the ground state ...
and the other in a specific
excited state
In quantum mechanics
Quantum mechanics is the fundamental physical Scientific theory, theory that describes the behavior of matter and of light; its unusual characteristics typically occur at and below the scale of atoms. Reprinted, Add ...
.
Absorption band
In spectroscopy, an absorption band is a range of wavelengths, frequency, frequencies or energies in the electromagnetic spectrum that are characteristic of a particular transition from initial to final state in a substance.
According to quantum ...
s of O
4 e.g. at 360, 477 and 577 nm are frequently used to achieve
aerosol inversions in atmospheric optical
absorption spectroscopy
Absorption spectroscopy is spectroscopy that involves techniques that measure the absorption of electromagnetic radiation, as a function of frequency or wavelength, due to its interaction with a sample. The sample absorbs energy, i.e., photons ...
. Due to the known distribution of O
2 and therefore also O
4, O
4 slant column densities can be used to retrieve
aerosol
An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be generated from natural or Human impact on the environment, human causes. The term ''aerosol'' co ...
profiles which can then be used again in
radiative transfer models to model light paths.
[
]
Potential use
Though its use is highly speculative due to its unstable nature, it has been theorized that tetraoxygen could be used as an alternative to traditional
liquid oxygen
Liquid oxygen, sometimes abbreviated as LOX or LOXygen, is a clear cyan liquid form of dioxygen . It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an application which is ongoing.
Physical ...
in
rocket propulsion
A rocket (from , and so named for its shape) is a vehicle that uses jet propulsion to Acceleration, accelerate without using any surrounding Atmosphere of Earth, air. A rocket engine produces thrust by Reaction (physics), reaction to exhaust ex ...
. Its higher density—approximately twice that of liquid oxygen—could allow for smaller oxidizer tanks, reducing overall vehicle mass and potentially increasing payload capacity.
See also
*
Tetranitrogen (N
4)
*
Solid oxygen
*
Liquid oxygen
Liquid oxygen, sometimes abbreviated as LOX or LOXygen, is a clear cyan liquid form of dioxygen . It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an application which is ongoing.
Physical ...
References
{{oxygenallotropes
Allotropes of oxygen
2001 in science
de:Allotrope Formen von Sauerstoff#Tetrasauerstoff