Landé g-factor

Landé g-factor

In physics, the Landé g-factor is a particular example of a g-factor, namely for an electron with both spin and orbital angular momenta. It is named after Alfred Landé, who first described it in 1921.

In atomic physics, it is a multiplicative term appearing in the expression for the energy levels of an atom in a weak magnetic field. The quantum states of electrons in atomic orbitals are normally degenerate in energy, with the degenerate states all sharing the same angular momentum. When the atom is placed in a weak magnetic field, however, the degeneracy is lifted.

The factor comes about during the calculation of the first-order perturbation in the energy of an atom when a weak uniform magnetic field (that is, weak in comparison to the system's internal magnetic field) is applied to the system. Formally we can write the factor as,

:g_J= g_Lfrac{J(J+1)-S(S+1)+L(L+1)}{2J(J+1)}+g_Sfrac{J(J+1)+S(S+1)-L(L+1)}{2J(J+1)} : approx 1+frac{J(J+1)-L(L+1)+S(S+1)}{2J(J+1)}

:g_L = 1 , g_Sapprox 2

Here, "J" is the total electronic angular momentum, "L" is the orbital angular momentum, and "S" is the spin angular momentum. Because "S"=1/2 for electrons, one often sees this formula written with 3/4 in place of "S"("S"+1). The quantities "gL" and "gS" are other g-factors of an electron.

If we wish to know the g-factor for an atom with total atomic angular momentum F=I+J,

:g_F= g_Jfrac{F(F+1)-I(I+1)+J(J+1)}{2F(F+1)}+g_Ifrac{F(F+1)+I(I+1)-J(J+1)}{2F(F+1)}

:approx g_Jfrac{F(F+1)-I(I+1)+J(J+1)}{2F(F+1)}

This last approximation is justified because g_I is smaller than g_J by the ratio of the electron mass to the proton mass.


Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • Factor de Landé — Saltar a navegación, búsqueda En mecánica cuántica existe un efecto llamado Zeeman que consiste en el desdoblamiento de niveles de energía en un átomo cuando se aplica un campo magnético externo. Cuando el campo es lo bastante débil, podemos… …   Wikipedia Español

  • Lande — may refer to:*Lande (surname) *Lande (village), Norway *Château de la Lande, France *Landé g factor …   Wikipedia

  • Landé’s splitting factor — g daugiklis statusas T sritis fizika atitikmenys: angl. Landé’s splitting factor vok. Aufspaltungsfaktor, m; Landé Faktor, m rus. g фактор, m; множитель Ланде, m; фактор расщепления Ланде, m pranc. facteur de Landé, m; facteur g de Landé, m …   Fizikos terminų žodynas

  • Landé-Faktor — g daugiklis statusas T sritis fizika atitikmenys: angl. Landé’s splitting factor vok. Aufspaltungsfaktor, m; Landé Faktor, m rus. g фактор, m; множитель Ланде, m; фактор расщепления Ланде, m pranc. facteur de Landé, m; facteur g de Landé, m …   Fizikos terminų žodynas

  • Landé-Faktor — atomo g daugiklis statusas T sritis Standartizacija ir metrologija apibrėžtis Apibrėžtį žr. priede. priedas( ai) Grafinis formatas atitikmenys: angl. g factor of atom; g factor of electron vok. Landé Faktor, m; Landéscher g Faktor, m rus. g… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • Landé-Rotationsfaktor — sukimosi g daugiklis statusas T sritis fizika atitikmenys: angl. rotational g factor vok. Landé Rotationsfaktor, m rus. вращательный множитель Ланде, m pranc. facteur g de rotation, m …   Fizikos terminų žodynas

  • g-factor (physics) — For the acceleration related quantity in mechanics, see g force. A g factor (also called g value or dimensionless magnetic moment) is a dimensionless quantity which characterizes the magnetic moment and gyromagnetic ratio of a particle or nucleus …   Wikipedia

  • Alfred Landé — (13 December, 1888 ndash;30 October 1976) was a German American physicist known for his contributions to quantum theory. He is responsible for the Landé g factor and an explanation of the Zeeman Effect.Life and AchievementsAlfred Landé was born… …   Wikipedia

  • G-factor — For the acceleration related quantity in mechanics, see g force. A g factor (also called g value or dimensionless magnetic moment) is a dimensionless quantity which characterizes the magnetic moment and gyromagnetic ratio of a particle or nucleus …   Wikipedia

  • facteur de Landé — g daugiklis statusas T sritis fizika atitikmenys: angl. Landé’s splitting factor vok. Aufspaltungsfaktor, m; Landé Faktor, m rus. g фактор, m; множитель Ланде, m; фактор расщепления Ланде, m pranc. facteur de Landé, m; facteur g de Landé, m …   Fizikos terminų žodynas

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”