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Description
In a multistep photoexcitation process, the excitation efficiency from the ground state to a final state depends on the polarization of the excitation photons, the angular momentum of the intermediate state and of the final state. Most experimental work on the polarization dependence in resonance ionization has been performed in atomic beams, where polarization relaxation due to collisional interaction is negligible. For ISOL type hot cavity laser ion sources however these ideal conditions do not necessarily exist.
Using TRIUMF’s off-line laser ion source test stand with a system of tunable titanium sapphire lasers, we investigated the polarization-dependence of laser resonance ionization in Be and Cd – using our preferred laser ionization schemes. A significant polarization dependence of the ion signal was confirmed in the typical excitation ladder $^1$S$_0$→$^1$P$_1$→$^1$S$_0$ for alkaline and alkaline-like elements. Polarization as an important parameter in optimizing laser ion source operation will be discussed. The use of polarization spectroscopy to determine the J values of the newly found states in the spectra of elements with complex electronic structure or only radioactive isotopes, $\textit{e.g.}$, Ra, Sm, Yb, Pu and No will be explained.
