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  2. Helium dimer - Wikipedia

    en.wikipedia.org/wiki/Helium_dimer

    The binding energy is only about 1.3 mK, 10 −7 eV [6] [7] [8] or 1.1×10 −5 kcal/mol. [9] Both helium atoms in the dimer can be ionized by a single photon with energy 63.86 eV. The proposed mechanism for this double ionization is that the photon ejects an electron from one atom, and then that electron hits the other helium atom and ionizes ...

  3. Magneto-optical trap - Wikipedia

    en.wikipedia.org/wiki/Magneto-optical_trap

    A MOT cloud in two different density regimes:If the density of the MOT is high enough, the MOT cloud goes from having a Gaussian density distribution (left), to something more exotic (right). In the right hand image, the density is so high that atoms have been blown out of the central trapping region by radiation pressure, to then form a ...

  4. Molecular orbital diagram - Wikipedia

    en.wikipedia.org/wiki/Molecular_orbital_diagram

    In agreement with this description the photoelectron spectrum for water shows a sharp peak for the nonbonding 1b 1 MO (12.6 eV) and three broad peaks for the 3a 1 MO (14.7 eV), 1b 2 MO (18.5 eV) and the 2a 1 MO (32.2 eV). [29] The 1b 1 MO is a lone pair, while the 3a 1, 1b 2 and 2a 1 MO's can be localized to give two O−H bonds and an in-plane ...

  5. Molecular orbital - Wikipedia

    en.wikipedia.org/wiki/Molecular_orbital

    The qualitative approach of MO analysis uses a molecular orbital diagram to visualize bonding interactions in a molecule. In this type of diagram, the molecular orbitals are represented by horizontal lines; the higher a line the higher the energy of the orbital, and degenerate orbitals are placed on the same level with a space between them.

  6. Molecular orbital theory - Wikipedia

    en.wikipedia.org/wiki/Molecular_orbital_theory

    Molecular orbital diagram of He 2 Bond order is the number of chemical bonds between a pair of atoms. The bond order of a molecule can be calculated by subtracting the number of electrons in anti-bonding orbitals from the number of bonding orbitals, and the resulting number is then divided by two.

  7. Antibonding molecular orbital - Wikipedia

    en.wikipedia.org/wiki/Antibonding_molecular_orbital

    The higher-energy orbital is the antibonding orbital, which is less stable and opposes bonding if it is occupied. In a molecule such as H 2, the two electrons normally occupy the lower-energy bonding orbital, so that the molecule is more stable than the separate H atoms. He 2 electron configuration. The four electrons occupy one bonding orbital ...

  8. Isotopes of helium - Wikipedia

    en.wikipedia.org/wiki/Isotopes_of_helium

    1 H + 1 H + 1.25 MeV → 2 He; then the diproton immediately beta-plus decays into deuterium: 2 He → 2 H + e + + ν e + 1.67 MeV; with the overall formula 1 H + 1 H → 2 H + e + + ν e + 0.42 MeV. The hypothetical effect of a bound diproton on Big Bang and stellar nucleosynthesis, has been investigated. [18]

  9. Frontier molecular orbital theory - Wikipedia

    en.wikipedia.org/wiki/Frontier_molecular_orbital...

    To use FMO theory, the reaction should be considered as two separate ideas: (1) whether or not the reaction is allowed, and (2) which mechanism the reaction proceeds through. In the case of a [1,5] shift on pentadiene, the HOMO of the sigma bond (i.e., a constructive bond) and the LUMO of butadiene on the remaining 4 carbons is observed.