Bohr magneton

In atomic physics, the Bohr magneton (symbol $Î¼ B$ ) is a physical constant of magnetic moment of electrons. It was discovered in 1913 by Romanian physicist Åžtefan Procopiu^[1] and rediscovered independently two years later by Danish physicist Niels Bohr. It is sometimes called the Bohr-Procopiu magneton.

The Bohr magneton is defined in SI units by

$\mu_\mathrm{B} = {{e \hbar} \over {2 m_\mathrm{e}}}$

and in Gaussian centimeter-gram-second units by

$\mu_\mathrm{B} = {{e \hbar} \over {2 m_\mathrm{e} c}}$

where

e

is the elementary charge,

$\hbar$ is the reduced Planck constant,

m e

is the electron rest mass

c

is the speed of light.

In the SI system of units its value is^[2]

Î¼ B

= 9.274 009 15(23) í— 10^-24 J-T^-1.

(The units, J-T^-1, can also be written as A-m², or as C-m²-s^-1.)

In the eV system of units its value is

Î¼ B

= 5.7883 í— 10^-5 eV-T^-1.

In the CGS system of units its value is

Î¼ B

= 9.274 009 15(23) í— 10^-21 Erg-Oe^-1^[3]

In atomic units, the Bohr magneton is Î¼_B=1/2.

The Bohr magneton is the natural unit for expressing an electron magnetic dipole moment. An electron has an intrinsic magnetic dipole moment of approximately one Bohr magneton.^[4]

[] References

^ Åžtefan Procopiu - Determining the Molecular Magnetic Moment by M. Planck's Quantum Theory - Bulletin scientifique de l'Académie roumaine de sciences, Bucharest, 1913
^ CODATA
^ Robert C. O'Handley (2000). Modern magnetic materials: principles and applications. John Wiley & Sons. ISBN 0-471-15566-7 page 83
^ A. Mahajan and A. Rangwala. Electricity and Magnetism, p. 419 (1989). Via Google Books.

[] See also