Trace determination of 90Sr and 89Sr in environmental samples by collinear resonance ionization spectroscopy

Abstract

Collinear resonance ionization spectroscopy has been developed as a sensitive technique for fast trace detection of 90Sr and 89Sr in the environment. A detection limit for 90Sr of 107 atoms in the presence of 1017 atoms in the presence of 1017 atoms of stable Strontium has been achieved, while the applicability of the method has been demonstrated on real world samples. After collection and chemical separation, strontium is surface ionized, accelerated to 33keV and mass separated. The ions are neutralized and the emerging fast atoms interact with an argon ion laser beam (γ=364 nm) in a quasi‐collinear geometry. Optical excitation starts from the long‐lived 5s4d3 D2 state of strontium, which is populated in the charge exchange process, and the fast atoms are selectively excited into the high‐lying 5s23f3F3 Rydberg state. The Rydberg‐atoms are subsequently field‐ionized and detected by a channeltron detector after energy selection. The described method was successfully used to determine the 90Sr‐content in a...