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  2. Rydberg formula - Wikipedia

    en.wikipedia.org/wiki/Rydberg_formula

    In 1890, Rydberg proposed on a formula describing the relation between the wavelengths in spectral lines of alkali metals. [2]: v1:376 He noticed that lines came in series and he found that he could simplify his calculations using the wavenumber (the number of waves occupying the unit length, equal to 1/λ, the inverse of the wavelength) as his unit of measurement.

  3. Full width at half maximum - Wikipedia

    en.wikipedia.org/wiki/Full_width_at_half_maximum

    Full width at half maximum. In a distribution, full width at half maximum (FWHM) is the difference between the two values of the independent variable at which the dependent variable is equal to half of its maximum value.

  4. Balmer series - Wikipedia

    en.wikipedia.org/wiki/Balmer_series

    The equation commonly used to calculate the Balmer series is a specific example of the Rydberg formula and follows as a simple reciprocal mathematical rearrangement of the formula above (conventionally using a notation of m for n as the single integral constant needed):

  5. Characteristic X-ray - Wikipedia

    en.wikipedia.org/wiki/Characteristic_X-ray

    For all elements, the ratio of the intensities of K-alpha 1 and K-alpha 2 is very close to 2:1. [7] An example of K-alpha lines is Fe K-alpha emitted as iron atoms are spiraling into a black hole at the center of a galaxy. [8] The K-alpha line in copper is frequently used as the primary source of X-ray radiation in lab-based X-ray diffraction ...

  6. Cross section (physics) - Wikipedia

    en.wikipedia.org/wiki/Cross_section_(physics)

    Figure 1. In a gas of particles of individual diameter 2 r , the cross section σ , for collisions is related to the particle number density n , and mean free path between collisions λ . In a gas of finite-sized particles there are collisions among particles that depend on their cross-sectional size.

  7. Probability amplitude - Wikipedia

    en.wikipedia.org/wiki/Probability_amplitude

    Intuitively, since a normalised wave function stays normalised while evolving according to the wave equation, there will be a relationship between the change in the probability density of the particle's position and the change in the amplitude at these positions. Define the probability current (or flux) j as

  8. Wavenumber - Wikipedia

    en.wikipedia.org/wiki/Wavenumber

    In the physical sciences, the wavenumber (or wave number), also known as repetency, [1] is the spatial frequency of a wave. Ordinary wavenumber is defined as the number of wave cycles divided by length; it is a physical quantity with dimension of reciprocal length , expressed in SI units of cycles per metre or reciprocal metre (m −1 ).

  9. Spin contamination - Wikipedia

    en.wikipedia.org/wiki/Spin_contamination

    In computational chemistry, spin contamination is the artificial mixing of different electronic spin-states. This can occur when an approximate orbital-based wave function is represented in an unrestricted form – that is, when the spatial parts of α and β spin-orbitals are permitted to differ. Approximate wave functions with a high degree ...