Resonance absorption spectroscopy for laser-ablated lanthanide atom, 1; Optimized experimental conditions for isotope-selective absorption of gadolinium (Contract research)

Miyabe, Masabumi   ; Oba, Masaki ; Iimura, Hideki  ; Akaoka, Katsuaki ; Maruyama, Yoichiro; Wakaida, Ikuo  ; Watanabe, Kazuo

For remote isotope analysis of low-decontaminated TRU fuel, we are developing an analytical technique on the basis of the resonance absorption spectroscopy for the laser-ablation plume. To improve isotopic selectivity and detection sensitivity of this technique, we measured absorption spectra of Gd atom with various conditions. As a result, high resolution spectrum was obtained from the observation of slow component of the plume produced under low-pressure rare-gas ambient. The observed narrowest linewidth of about 0.85 GHz was found to be close to the Doppler width estimated for Gd atom of room temperature. Furthermore, relaxation rate of higher meta-stable state was found to be faster than that of ground state, suggesting that use of the transition arising from ground state or lower meta-stable state is preferable for highly sensitive isotope analysis.