Atom Trap Trace Analysis For Rare Gas Atomic Isotopes

Trace analysis of radioactive isotopes has played an important role in the ap-plications of geological dating, environmental safety and life sciences. Considerable progress has been achieved to establish new analysis techniques and to apply new iso-tope species. Kr-81(t1/2=2.3x105years, isotopic abundance1x10-12) is produced by cosmic rays in the upper atmosphere. It is an ideal tracer for dating ice and groundwa-ter in the age range of0.05-1million years. Kr-85(t1/2=10.8years, isotopic abundance2×10-11), is a fission product. Both krypton isotopes can be used in the studies of the replenishment, transfer and circulation of groundwater.The present dissertation is contributed to setting up an apparatus for single Kr atom detection as a tool for atom trap trace analysis. Improvements are accomplished to increase the atomic beam flux and the loading rate of the atom trap. To improve the quantitative capability of the ATTA method, a new calibration methodology based on resonance laser quenching is proposed and the performance is tested by measuring the relative Kr isotope abundance of a natural Kr sample. In present studies, laser fre-quency locking and precision spectroscopy techniques have been developed and they are applied to establish a precision cavity ring-down spectrometer. High-precision spectroscopy of H2has been carried out and a most precise electric quadrupole ro-vibrational transition of H2has been obtained.The dissertation is organized as following:In the first chapter, we present the fundamentals of radio-krypton isotopes analy-sis. The principle and related strategy of atom trap trace analysis are presented.In the second chapter, the apparatus for atom trap trace analysis is introduced. The improvements on the experimental setup including an enhanced atomic beam flux and trap loading rate are presented together with the measurements and results.The process for sample measurement with ATTA is described in chapter three. The idea of the resonance laser quenching used for calibration is presented together with the experimental establishment. Finally, potential improvements and prospects on the present apparatus and ATTA are given.In chapter four, the high-precision and high-sensitivity cavity ring-down spec- troscopy is introduced and the precision spectroscopy of H2O and H2molecular tran-sitions near795nm is presented.