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Helium is the least water-soluble monatomic gas, [96] and one of the least water-soluble of any gas (CF 4, SF 6, and C 4 F 8 have lower mole fraction solubilities: 0.3802, 0.4394, and 0.2372 x 2 /10 −5, respectively, versus helium's 0.70797 x 2 /10 −5), [97] and helium's index of refraction is closer to unity than that of any other gas. [98]
The higher the temperature of the gas, the wider the distribution of velocities in the gas. Since the spectral line is a combination of all of the emitted radiation, the higher the temperature of the gas, the broader the spectral line emitted from that gas. This broadening effect is described by a Gaussian profile and there is no associated shift.
[4] [5] Fowler managed to produce similar lines from a hydrogen–helium mixture in 1912, and supported Pickering's conclusion as to their origin. [6] Niels Bohr , however, included an analysis of the series in his 'trilogy' [ 7 ] [ 8 ] on atomic structure [ 9 ] and concluded that Pickering and Fowler were wrong and that the spectral lines ...
The Fraunhofer lines are typical spectral absorption lines. Absorption lines are narrow regions of decreased intensity in a spectrum, which are the result of photons being absorbed as light passes from the source to the detector. In the Sun, Fraunhofer lines are a result of gas in the Sun's atmosphere and outer photosphere. These regions have ...
Spectral line shape or spectral line profile describes the form of an electromagnetic spectrum in the vicinity of a spectral line – a region of stronger or weaker intensity in the spectrum. Ideal line shapes include Lorentzian , Gaussian and Voigt functions, whose parameters are the line position, maximum height and half-width. [ 1 ]
An emission spectrum is formed when an excited gas is viewed directly through a spectroscope. Schematic diagram of spontaneous emission Emission spectroscopy is a spectroscopic technique which examines the wavelengths of photons emitted by atoms or molecules during their transition from an excited state to a lower energy state.
Spectroscopists customarily refer to the spectrum arising from a given ionization state of a given element by the element's symbol followed by a Roman numeral.The numeral I is used for spectral lines associated with the neutral element, II for those from the first ionization state, III for those from the second ionization state, and so on. [1]
Helium has a diffuse series of doublet lines with wavelengths 5876, 4472 and 4026 Å. Helium when ionised is termed He II and has a spectrum very similar to hydrogen but shifted to shorter wavelengths. This has a diffuse series as well with wavelengths at 6678, 4922 and 4388 Å.