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Hydrogen line

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The hydrogen line, 21 centimeter line, or H I line is a spectral line that is created by a change in the energy state of solitary, electrically neutral hydrogen atoms. It is produced by a spin-flip transition, which means the direction of the electron's spin is reversed relative to the spin of the proton. This is a quantum state change between the two hyperfine levels of the hydrogen 1 s ground state. The electromagnetic radiation producing this line has a frequency of 1420.405751768(2) MHz (1.42 GHz), which is equivalent to a wavelength of 21.106114054160(30) cm in a vacuum. According to the Planck–Einstein relation E = hν, the photon emitted by this transition has an energy of 5.8743261841116(81) μeV [9.411708152678(13)×10−25 J]. The constant of proportionality, h, is known as the Planck constant.

Hydrogen line - Wikipedia Jump to content From Wikipedia, the free encyclopedia Spectral line of hydrogen state transition in UHF radio frequencies For hydrogen lines in general, see hydrogen spectral series . 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 . It is produced by a spin -flip transition, wh

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