Date of Award
Doctor of Philosophy
Reliable and safe application of isotopes as tracers is important in many areas, including biomedical, environmental and geochrono- logical sciences. A new approach to stable-isotope ratio analysis based on atomic hyperfine structure is demonstrated. This laser spectroscopic scheme is virtually interference-free because of the highly selective and specific nature of hyperfine structures. Hence, a minor constituent in a complex matrix can be selectively analyzed without extensive sample preparation. A single-frequency tunable cw ring dye laser is used as the excitation source and a specially designed and constructed demountable cathode discharge is used as the atomizer and detector. Samples are electrodeposited on the demountable cathode and hyperfine profiles are collected by optogalvanic detection. By spectral deconvolution, the relative abundances of all isotopes present can be determined with good accuracy and precision. The technique is demonstrated for copper concentrations as low as 1.6 ppm, using the atomic hyperfine structure of Cu I 578.2 nm non-resonance transition. It is also successfully tested for analysis of copper isotopes in human blood;The sensitivity of Doppler-free polarization spectroscopy in atomic flames is demonstrated to be competitive with other sensitive laser techniques such as the fluorescence spectrometric methods. Improved detectability of polarization rotation and excellent suppression of flame background noise enable this method to achieve detection limits of parts per trillion levels of sodium and 37 ppb of barium, while taking advantage of the convenient sample introduction of analytical flames. Furthermore, since polarization spectroscopy provides Doppler-free information, the spectral;resolution is suitable for isotopic analysis, and the technique offers excellent selectivity and minimum spectral interference; ('1)DOE Report IS-T-1156. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
William G. Tong
Tong, William G., "New laser spectroscopic technique for stable-isotope ratio analysis " (1984). Retrospective Theses and Dissertations. 8222.