Development of cavity ring-down spectroscopy apparatus for chemical identification of carrier-free radioiodine and astatine in gas phase

Toyoshima, Atsushi; Aoyagi, Noboru   

Although carrier-free radiotracers are utilized in lots of research fields, their chemical forms have not been identified by UV/vis. spectroscopy because of their micro quantities. In this study, we are developing an apparatus for cavity ring-down spectroscopy to perform absorption spectroscopy of radioiodine and astatine in a gas-phase. With this apparatus, ultra-sensitive absorption measurement is realized by making injected pulse-laser go back and forth tens of thousand times between facing mirrors. Intensity of laser in the cavity becomes weaker by its escaping through the mirrors and by absorption by samples. Absorption coefficients are obtained from difference in the life-time of escaped light between blank and sample measurements. Chemical species are expected to be characterized by measuring absorption coefficients at various wavelength and comparing these with known spectra and theoretical calculations. In the symposium, present status of the development will be reported.