# Chemicals/Oxygens

"Molecular oxygen (O$_2$) [is] a colorless, odorless gas at room temperature."

## Emissions

"[A]irglow emissions [have been] measured by using vertical-viewing photometers [for the] O($^1$S) green line at 557.7 nm [with a] background at 566 nm".
The O III emission lines are at 495.9 and 500.7 nm.
Oxygen has an emission line that occurs in plasmas at 527.62 nm from O IV.
Oxygen (O I) has two red lines at 630.0 and 636.4 nm. In the red there are the atomic oxygen transitions of the "forbidden oxygen red doublet at 6300.304 and 6363.776 Å ($^1$D - $^3$P)". Atmospheric O$_2$ has a red line at 686.72 nm.
"The oxygen abundance [may be determined] using the oxygen forbidden line at 630nm". "[R]atios [of] O/Fe ... are in agreement with the ratios found in the metal-poor red giants, suggesting that no real difference exists between dwarfs and giants."
"The forbidden oxygen line (λ 630.03nm) is weak in dwarf stars"
In the spectrum at right several red astronomy emission lines are detected and recorded at normalized intensities (to the oxygen III line) from the Ring Nebula. In the red are the two forbidden lines of oxygen ([O I], 630.0 and 636.4 nm), two forbidden lines of nitrogen ([N II], 654.8 nm and [N II], 658.4 nm), the hydrogen line (Hα, 656.3 nm) and a forbidden line of sulfur ([S II], 671.7 nm).
The spectrum above shows the lines in the visible due to emission from elemental oxygen.
Oxygen has several emission lines that occur in an electron cyclotron resonance (ECR) heated plasmas: 406.963, 406.99, 407.22, 407.59, 407.89, 408.51, 435.12, 441.489, and 441.697 nm from O II, and 434.045 nm from O VIII.

## Electrons

"Electron temperatures are generally derived from the ratio of auroral to nebular lines in [O III] or [N II]." "[B]ecause of the proximity of strong night-sky lines at λ4358 and λλ5770, 5791, the auroral lines of [O III] λ4363 and [N II] λ5755 are often contaminated."

## Gases

Allotropes of oxygen:
* molecular oxygen (O$_2$), present at significant levels in Earth's atmosphere.
* ozone (O$_3$).
* Atomic oxygen (O$_1$).
* Singlet oxygen (O$_2$*), one of two metastable states of molecular oxygen.
* Tetraoxygen (O$_4$), a metastable form.

## Carbon monoxide

"The Antennae Galaxies (also known as NGC 4038 and 4039) are a pair of distorted colliding spiral galaxies about 70 million light-years away, in the constellation of Corvus (The Crow). This view combines ALMA observations, made in two different wavelength ranges during the observatory’s early testing phase, with visible-light observations from the NASA/ESA Hubble Space Telescope."
"The Hubble image is the sharpest view of this object ever taken and serves as the ultimate benchmark in terms of resolution. ALMA observes at much longer wavelengths which makes it much harder to obtain comparably sharp images. However, when the full ALMA array is completed its vision will be up to ten times sharper than Hubble."
"Most of the ALMA test observations used to create this image were made using only twelve antennas working together — far fewer than will be used for the first science observations — and much closer together as well. Both of these factors make the new image just a taster of what is to come. As the observatory grows, the sharpness, speed, and quality of its observations will increase dramatically as more antennas become available and the array grows in size. This is nevertheless the best submillimetre-wavelength image ever taken of the Antennae Galaxies and opens a new window on the submillimetre Universe."
"While visible light — shown here mainly in blue — reveals the newborn stars in the galaxies, ALMA’s view shows us something that cannot be seen at those wavelengths: the clouds of dense cold gas from which new stars form. The ALMA observations — shown here in red, pink and yellow — were made at specific wavelengths of millimetre and submillimetre light (ALMA bands 3 and 7), tuned to detect carbon monoxide molecules in the otherwise invisible hydrogen clouds, where new stars are forming."
"Massive concentrations of gas are found not only in the hearts of the two galaxies but also in the chaotic region where they are colliding. Here, the total amount of gas is billions of times the mass of the Sun — a rich reservoir of material for future generations of stars."

## Liquids

Liquid oxygen as shown on the right may not be perfectly clear.
"Liquid oxygen has a pale blue color and is strongly paramagnetic and can be suspended between the poles of a powerful horseshoe magnet. Liquid oxygen has a density of 1.141 kg/L and is cryogenic. [F]reezing point: 50.5 K (-368.77 °F; -222.65 °C), boiling point: 90.19 K (-297.33 °F, -182.96 °C) at 101.325 kPa (760 mmHg)."

## Solids

Solid oxygen, existing in six variously colored phases, of which one is O $_8$ and another one metallic:
   * α-phase: light blue forms at 1 atm, below 23.8 K, monoclinic crystal structure.
   * β-phase: faint blue to pink forms at 1 atm, below 43.8 K, rhombohedral crystal structure (at room temperature and high pressure begins transformation to tetraoxygen).
   * γ-phase: faint blue forms at 1 atm, below 54.36 K, cubic crystal structure.
   * δ-phase: orange forms at room temperature at a pressure of 9 GPa.
   * ε-phase: dark-red to black forms at room temperature at pressures greater than 10 GPa.
   * ζ-phase: metallic forms at pressures greater than 96 GPa.

## Strontium oxides

Strontium oxide or strontia, SrO, is formed when strontium reacts with oxygen.

## Minerals

Minerals that are approximately 50 atomic % oxygen may be alloys.

## Akaganeites

Akaganeites have the chemical formula Fe$^{3+}$ O(OH,Cl).
Akaganeite (International Mineralogical Association (IMA) symbol: Akg), also written as the deprecated Akaganéite, is a chloride-containing iron(III) oxide-hydroxide mineral, formed by the weathering of pyrrhotite (Fe $_{(1−x)}$S).
Akaganeite is often described as the β phase of anhydrous Iron(III) oxide-hydroxide (ferric oxyhydroxide) FeOOH, but some chloride (or fluoride) ions are normally included in the structure, so a more accurate formula is FeO $_{0.833}$(OH) $_{1.167}$Cl $_{0.167}$. Nickel may substitute for iron, yielding the more general formula (Fe$^{3+}$ ,Ni$^{2+}$ ) $_8$(OH,O) $_{16}$Cl $_{1.25}$
Akaganeite has a metallic luster and a brownish yellow streak, crystal structure is monoclinic and similar to that of hollandite BaMn $_8$O $_{16}$, characterised by the presence of tunnels parallel to the c-axis of the tetragonal lattice. These tunnels are partially occupied by chloride anions that give to the crystal its structural stability.
Occurrence: The mineral was discovered in the Akagane mine in Iwate, Japan, for which it is named. It was described by the Japanese mineralogist Matsuo Nambu in 1968, but named as early as 1961.
Akaganeite has also been found in widely dispersed locations around the world and in rocks from the Moon that were brought back during the Apollo Project. The occurrences in meteorites and the lunar sample are thought to have been produced by interaction with Earth's atmosphere. It has been detected on Mars through orbital imaging spectroscopy.

## Behoites

The natural pure beryllium hydroxide is rare (in form of the mineral behoite, orthorhombic) or very rare (clinobehoite, monoclinic).

## Bromellites

Bromellite is BeO, with 50 at % beryllium.

## Litharges

Litharge is one of the natural mineral forms of lead(II) oxide, PbO. Litharge is a secondary mineral which forms from the oxidation of galena ores. It is a coating and encrustation with internal tetragonal crystal structure. It is dimorphous with the orthorhombic form massicot. Z = 2.

## Massicots

Massicot is lead (II) oxide (PbO) mineral with an orthorhombic lattice structure, Z = 4.

## Auroras

"Since the early work of Ångström,* we have the published records of over a hundred investigations on the spectrum, and many others on the origin or other phenomena characteristic of the aurora." "Babcock, using a Fabry and Perot interferometer, determined very accurately the wave-length of the auroral green line 5577. ... After a careful examination of all the results obtained in these reports, we may only say that the exact nature of the cosmical rays, responsible for the aurora, remains a mystery. ... The origin of the most prominent and interesting line of the auroral spectrum, the line 5577, has hitherto remained unexplained. Vegard* has recently obtained a luminescent band from solid nitrogen, that he supposes, under very special conditions, may coincide with the auroral green line. ... spectra of pure helium and of pure oxygen were taken at different pressures and with various excitations, but no trace of 5577 or of any other new lines was obtained. ... Mixtures of helium, oxygen and nitrogen were excited, and it was found that the line 5577 could be photographed on the same plate with the nitrogen band system, thus reproducing in the laboratory practically the entire auroral spectrum. In ... mixtures of neon and oxygen ... neon enhanced the line 5577 in the same manner as helium. ... From Plate 20 it will be seen that all the lines except 5577 have been identified as strong lines in the spectrum of helium, hydrogen, oxygen, or mercury. ... It has been shown that this line must be attributed to some hitherto unknown spectrum of oxygen, and that it is not a limiting member of the ordinary band spectrum of oxygen. It has been observed faintly in highly purified oxygen when currents of high density have been used."

## Glaciology

"Oxygen-isotope analyses of ice and firn from the Saskatchewan Glacier, Canada, and the Malaspina Glacier, Alaska, show that variations in ratios are likely to be of considerable value in glaciological research."

## Technology

Plasma cleaning involves the removal of impurities and contaminants from surfaces through the use of an energetic plasma created from gaseous species. Gases such as argon and oxygen, as well as mixtures such as air and hydrogen/nitrogen are used. The plasma is created by using high frequency voltages (typically kHz to >MHz) to ionise the low pressure gas (typically around 1/1000 atmospheric pressure), although atmospheric pressure plasmas are now also common.

## Resources

* Actinides
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