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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 Greek letters ...
In the Bohr model, the Lyman series includes the lines emitted by transitions of the electron from an outer orbit of quantum number n > 1 to the 1st orbit of quantum number n' = 1. The series is named after its discoverer, Theodore Lyman , who discovered the spectral lines from 1906–1914.
Lyman-alpha, typically denoted by Ly-α, is a spectral line of hydrogen (or, more generally, of any one-electron atom) in the Lyman series. It is emitted when the atomic electron transitions from an n = 2 orbital to the ground state ( n = 1), where n is the principal quantum number .
The hydrogen line is produced when an electron in a neutral hydrogen atom is excited to the triplet spin state, or de-excited as the electron and proton spins go to the singlet state. The energy difference between these two hyperfine states is 5.9 × 10 − 6 {\displaystyle 5.9\times 10^{-6}} electron volts , with a wavelength of 21 centimeters.
A more accurate approach is to take into account that the operator of the magnetic moment of an electron is a sum of the contributions of the orbital angular momentum and the spin angular momentum, with each multiplied by the appropriate gyromagnetic ratio: = (+), where =, and (the anomalous gyromagnetic ratio, deviating from 2 due to the ...
A hydrogen molecule can absorb a far-ultraviolet photon (11.2 eV < energy of the photon < 13.6 eV) and make a transition from the ground electronic state X to excited state B (Lyman) or C (Werner). Radiative decay occurs rapidly. 10–15% of the decays occur into the vibrational continuum. This means that the hydrogen molecule has dissociated.
In the case of neutral atomic hydrogen, the minimum ionization energy is equal to the Lyman limit, where the photon has enough energy to completely ionize the atom, resulting in a free proton and a free electron. Above this energy (below this wavelength), all wavelengths of light may be absorbed. This forms a continuum in the energy spectrum ...
The Lyman-alpha forest was first discovered in 1970 by astronomer Roger Lynds in an observation of the quasar 4C 05.34. [1] Quasar 4C 05.34 was the farthest object observed to that date, and Lynds noted an unusually large number of absorption lines in its spectrum and suggested that most of the absorption lines were all due to the same Lyman-alpha transition. [2]