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Fractional Chern insulator: A generalization of fractional quantum Hall state to electrons on a lattice. Berezinskii-Kosterlitz-Thouless state: A 2D state with unbound vortex-antivortex pairs. String-net liquid: Atoms in this state have unstable arrangements, like a liquid, but are still consistent in the overall pattern, like a solid.
Oxygen-16 (symbol: 16 O or 16 8 O) is a nuclide. It is a stable isotope of oxygen, with 8 neutrons and 8 protons in its nucleus, and when not ionized, 8 electrons orbiting the nucleus. Oxygen-16 has a mass of 15.994 914 619 56 u. It is the most abundant isotope of oxygen and accounts for 99.757% of oxygen's natural abundance. [2]
The doublet state requires an odd number of electrons, and so cannot occur in dioxygen without gaining or losing electrons, such as in the superoxide ion (O − 2) or the dioxygenyl ion (O + 2). The ground state of O 2 has a bond length of 121 pm and a bond energy of 498 kJ/mol. [ 3 ] It is a colourless gas with a boiling point of −183 °C ...
The relative stability of the oxygen diradical is primarily due to the spin-forbidden nature of the triplet-singlet transition required for it to grab electrons, i.e., "oxidize". The diradical state of oxygen also results in its paramagnetic character, which is demonstrated by its attraction to an external magnet. [12]
The term symbol of an atomic state indicates its values of L, S, and J. As examples, the ground states of both the oxygen atom and the dioxygen molecule have two unpaired electrons and are therefore triplet states. The atomic state is described by the term symbol 3 P, and the molecular state by the term symbol 3 Σ − g.
2 into sugar in what is called a Calvin cycle. In nature, free oxygen is produced by the light-driven splitting of water during oxygenic photosynthesis. According to some estimates, green algae and cyanobacteria in marine environments provide about 70% of the free oxygen produced on Earth, and the rest is produced by terrestrial plants. [77]
Triplet oxygen, 3 O 2, refers to the S = 1 electronic ground state of molecular oxygen (dioxygen). Molecules of triplet oxygen contain two unpaired electrons, making triplet oxygen an unusual example of a stable and commonly encountered diradical : [ 2 ] it is more stable as a triplet than a singlet .
The molecule, therefore, has two unpaired electrons and is in a triplet state. In contrast, the first and second excited states of dioxygen are both states of singlet oxygen . Each has two electrons of opposite spin in the π* level so that S = 0 and the multiplicity is 2S + 1 = 1 in consequence.