Knowledge Bank

The Zeeman effect in the $111\to 116,212\to 211$ and $313\to 312$ transitions of and has been observed using magnetic field strength up to 11,000 gauss. All $\Delta m=\pm 1$ and $\Delta m=0$ transitions have been completely resolved. The spectra cannot be explained by only the first and higher order perturbations involving the elements in the molecular g-value tensor. The frequency shifts can be explained by including the quadratic field dependence involving the magnetic susceptibility tensor. The diagonal elements in the susceptibility tensor are found to be $Xas=(-6.2\pm 0.5)\times 10-6,Xbb=(-15.8\pm 0.4)\times 10-6$ and $Xee=(-23.0\pm 0.4)\times 10-6$ all in units of $erggauss2\times Mole$ The formerly known g-values have been redetermined with considerable improvement in accuracy. Both X and g-values can be used to deduce the elecronic ground state average value of the $\Sigma ixi2\Sigma iyi2$ and $\Sigma izi2$ operators, where $xi,yi$, and $zi$ are measured from the center of mass of the molecule and the sum is carried out over all electrons. The new experimental constants are valuable as a further check of electronic ground state functions. Computer calculations have been performed and the results will be discussed.