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  2. Hydrogen line - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_line

    A hydrogen atom with proton and electron spins aligned (top) undergoes a flip of the electron spin, resulting in emission of a photon with a 21 cm wavelength (bottom) The hydrogen line, 21 centimeter line, or H I line[ a ] is a spectral line that is created by a change in the energy state of solitary, electrically neutral hydrogen atoms.

  3. Fraunhofer lines - Wikipedia

    en.wikipedia.org/wiki/Fraunhofer_lines

    Solar spectrum with Fraunhofer lines as it appears visually. In 1802, English chemist William Hyde Wollaston [2] was the first person to note the appearance of a number of dark features in the solar spectrum. [3] In 1814, Joseph von Fraunhofer independently rediscovered the lines and began to systematically study and measure their wavelengths ...

  4. Absorption spectroscopy - Wikipedia

    en.wikipedia.org/wiki/Absorption_spectroscopy

    Absorption spectroscopy is spectroscopy that involves techniques that measure the absorption of electromagnetic radiation, as a function of frequency or wavelength, due to its interaction with a sample. The sample absorbs energy, i.e., photons, from the radiating field. The intensity of the absorption varies as a function of frequency, and this ...

  5. Spectral line - Wikipedia

    en.wikipedia.org/wiki/Spectral_line

    This is the spectrum of a blue sky somewhat close to the horizon, looking east with the sun to the west at around 3–4 pm on a clear day. A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum. It may result from emission or absorption of light in a narrow frequency range, compared with the nearby ...

  6. Spectral music - Wikipedia

    en.wikipedia.org/wiki/Spectral_music

    Definition. Defined in technical language, spectral music is an acoustic musical practice where compositional decisions are often informed by sonographic representations and mathematical analysis of sound spectra, or by mathematically generated spectra. The spectral approach focuses on manipulating the spectral features, interconnecting them ...

  7. Balmer series - Wikipedia

    en.wikipedia.org/wiki/Balmer_series

    The Balmer series, or Balmer lines in atomic physics, is one of a set of six named series describing the spectral line emissions of the hydrogen atom. The Balmer series is calculated using the Balmer formula, an empirical equation discovered by Johann Balmer in 1885. The visible spectrum of light from hydrogen displays four wavelengths, 410 nm ...

  8. Lyman series - Wikipedia

    en.wikipedia.org/wiki/Lyman_series

    Lyman series. In physics and chemistry, the Lyman series is a hydrogen spectral series of transitions and resulting ultraviolet emission lines of the hydrogen atom as an electron goes from n ≥ 2 to n = 1 (where n is the principal quantum number), the lowest energy level of the electron (groundstate). The transitions are named sequentially by ...

  9. Triple-alpha process - Wikipedia

    en.wikipedia.org/wiki/Triple-alpha_process

    As a side effect of the process, some carbon nuclei fuse with additional helium to produce a stable isotope of oxygen and energy: 12 6 C + 4 2 He → 16 8 O + γ (+7.162 MeV) Nuclear fusion reactions of helium with hydrogen produces lithium-5, which also is highly unstable, and decays back into smaller nuclei with a half-life of 3.7 × 10 −22 s.