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  2. Quantum defect - Wikipedia

    en.wikipedia.org/wiki/Quantum_defect

    The quantum defect may also be defined as follows: at a given frequency of pump and given frequency of lasing, the quantum defect = /; according to this definition, quantum defect is dimensionless. [ citation needed ] At a fixed pump frequency, the higher the quantum defect, the lower is the upper bound for the power efficiency.

  3. Non-stoichiometric compound - Wikipedia

    en.wikipedia.org/wiki/Non-stoichiometric_compound

    The composition of a non-stoichiometric compound usually varies in a continuous manner over a narrow range. Thus, the formula for wüstite is written as Fe 1−x O, where x is a small number (0.05 in the previous example) representing the deviation from the "ideal" formula. [3]

  4. Slater's rules - Wikipedia

    en.wikipedia.org/wiki/Slater's_rules

    If the group is of the [ns, np] type, an amount of 0.85 from each electron with principal quantum number (n–1), and an amount of 1.00 for each electron with principal quantum number (n–2) or less. If the group is of the [d] or [f], type, an amount of 1.00 for each electron "closer" to the nucleus than the group.

  5. Vacancy defect - Wikipedia

    en.wikipedia.org/wiki/Vacancy_defect

    Right circle points to a divacancy, i.e., sulfur atoms are missing both above and below the Mo layer. Other circles are single vacancies, i.e., sulfur atoms are missing only above or below the Mo layer. Scale bar: 1 nm. [1] In crystallography, a vacancy is a type of point defect in a crystal where an atom is missing from one of the lattice ...

  6. Donor number - Wikipedia

    en.wikipedia.org/wiki/Donor_number

    In chemistry a donor number (DN) is a quantitative measure of Lewis basicity.A donor number is defined as the negative enthalpy value for the 1:1 adduct formation between a Lewis base and the standard Lewis acid SbCl 5 (antimony pentachloride), in dilute solution in the noncoordinating solvent 1,2-dichloroethane with a zero DN.

  7. Degenerate energy levels - Wikipedia

    en.wikipedia.org/wiki/Degenerate_energy_levels

    The quantum numbers corresponding to these operators are , , (always 1/2 for an electron) and respectively. The energy levels in the hydrogen atom depend only on the principal quantum number n . For a given n , all the states corresponding to ℓ = 0 , … , n − 1 {\displaystyle \ell =0,\ldots ,n-1} have the same energy and are degenerate.

  8. Extent of reaction - Wikipedia

    en.wikipedia.org/wiki/Extent_of_reaction

    [1] The change in the extent of reaction is then defined as [2] [3] = where denotes the number of moles of the reactant or product and is the stoichiometric number [4] of the reactant or product. Although less common, we see from this expression that since the stoichiometric number can either be considered to be dimensionless or to have units ...

  9. Kröger–Vink notation - Wikipedia

    en.wikipedia.org/wiki/Kröger–Vink_Notation

    Kröger–Vink notation is a set of conventions that are used to describe electric charges and lattice positions of point defect species in crystals. It is primarily used for ionic crystals and is particularly useful for describing various defect reactions. It was proposed by Ferdinand Anne Kröger and Hendrik Jan Vink . [1] [2]