Polarization-dependent laser resonance ionization of beryllium

TL;DR

This study investigates how laser polarization affects resonance ionization of beryllium, revealing significant polarization dependence that impacts the operation of laser ion sources and enabling better spectroscopic analysis of complex elements.

Contribution

The paper demonstrates the polarization dependence in laser resonance ionization of beryllium and verifies it on radioactive isotopes, highlighting polarization as a key parameter in resonance ionization techniques.

Findings

Significant polarization dependence observed in beryllium ionization.

Verification of polarization effects on radioactive isotopes at TRIUMF.

Extraction of AI state energy and ionization potential of beryllium.

Abstract

Using TRIUMF's off-line laser ion source test stand with a system of tunable titanium sapphire lasers, the polarization dependence of laser resonance ionization has been investigated using beryllium. A significant polarization dependence was observed for the excitation path $^1$S$_0$$\rightarrow$$^1$P$^{\circ}_1$$\rightarrow$$^1$S$_0$, which are typical transitions for alkaline and alkaline-like elements. This polarization dependence was further verified on Be radioactive isotopes at TRIUMF's isotope separator and accelerator facility (ISAC). Laser polarization was proven to be an important parameter in operating resonance ionization laser ion sources (RILIS). The polarization spectroscopy was preformed off-line both on the 2p$^2$ $^1$S$_0$ autoionizing (AI) state and high-$n$ Rydberg states of the $2sns$ $^1S_0$ and $2snd$ $^1D_2$ series. The energy of the 2p$^2$ $^1$S$_0$ AI state and ionization potential (IP) of beryllium were extracted as 76167(6)~cm$^{-1}$ and 75192.59(3)~cm$^{-1}$. Polarization spectroscopy can be used to determine the $J$ values of newly found states in in-source spectroscopy of the complex/radioactive alkaline-like elements such as Ra, Sm, Yb, Pu and No.