Zeeman Splitting Method

If the atoms and molecules are permeated by magnetic field $B$, in the normal Zeeman splitting, the transition splits into three lines

$\displaystyle \nu_1$ $\textstyle =$ $\displaystyle \nu_0-\beta \vert B\vert,$ (4.35)
$\displaystyle \nu_2$ $\textstyle =$ $\displaystyle \nu_0,$ (4.36)
$\displaystyle \nu_3$ $\textstyle =$ $\displaystyle \nu_0+\beta \vert B\vert,$ (4.37)

where $\beta=e \hbar /2 m_e=1.3996{\rm Hz  \mu G^{-1}}$ is the Bohr magneton constant. This comes from the fact that the upper and lower levels are splited into $U_m=m_l\beta B$ using the magnetic quantum number $m_l$. HI $\lambda=21$cm, OH (maser emissions and thermally excited emissions), H$_2$O maser emissions are used to measure the magnetic field strength. Figure 4.4 represents the correlation between the magnetic field strength and gas density compiled by Fiebig & Guesten (1989), which indicates that $B$ is approximately proportional to $\rho^{1/2}$

Figure 4.4:
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\epsfxsize =.45\columnwidth \epsfbox{eps/fiebig1989-4-1.ps}\end{figure}

Kohji Tomisaka 2012-10-03