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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. Gaussian function - Wikipedia

    en.wikipedia.org/wiki/Gaussian_function

    A Gaussian function is the wave function of the ground state of the quantum harmonic oscillator. The molecular orbitals used in computational chemistry can be linear combinations of Gaussian functions called Gaussian orbitals (see also basis set (chemistry)).

  4. Balmer series - Wikipedia

    en.wikipedia.org/wiki/Balmer_series

    The red H-alpha spectral line of the Balmer series of atomic hydrogen, which is the transition from the shell n = 3 to the shell n = 2, is one of the conspicuous colours of the universe. It contributes a bright red line to the spectra of emission or ionisation nebula, like the Orion Nebula , which are often H II regions found in star forming ...

  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. 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.

  7. 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.

  8. 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

  9. Decay scheme - Wikipedia

    en.wikipedia.org/wiki/Decay_scheme

    The decay scheme of a radioactive substance is a graphical presentation of all the transitions occurring in a decay, and of their relationships. Examples are shown below. It is useful to think of the decay scheme as placed in a coordinate system, where the vertical axis is energy, increasing from bottom to top, and the horizontal axis is the proton number, increasing from left to right.