Trace Isotope Analysis of Rubidium, Cesium and Potassium with Degenerate Four-wave Mixing Method in Environmental Application

Isotope analysis is significant in environmental studies. In this work, degenerate four-wave mixing (DFWM) is employed to analyze atomic isotopes and the hyperfine structures of Rubidium (Rb), Cesium (Cs) and potassium (K) isotopes. The results show that isotopes and hyperfine structures of the three samples are clearly resolved. In addition, the isotope ratio obtained with DFWM is very close to that obtained by Mass-Spectrometry. Besides, low detection limit as 20.5 fg/ml, 1.3 pg/mL and 0.21 fg/mL were achieved for Rb, Cs and K respectively. Isotope-level resolution, trace-level sensitivity and isotope ratio measuring feasibility indicate that DFWM is a potential spectroscopic technique in isotopic trace analysis in environmental application.