[PPS07-P08] Development of cryogenic SIMS technique for isotope analysis of fluid inclusions
Keywords:Fluid inclusion, Cryogenic SIMS, Oxygen isotope
Changes of sample preparation procedures: The sample preparation system for cryogenic SIMS is composed of a cryo-polisher and Au ion-coater in a glove box . The temperature of polishing set to –35 °C. Thus frost condensation on the polished surface was prevented. After polishing, the sample was settled on the bottom of deep well of new designed cryo-coating stage. The cryo-coating stage was precooled to –196 °C by liquid nitrogen and the deep well was filled with cool nitrogen gas evaporated from liquid nitrogen in order to prevent frost formation on sample surface. This cooling process is necessary because sublimation temperature of ice is –50 °C during Au coating. The sample temperature was estimated to –196 °C before taking into the Au coater and warmed up –130 °C at taking from the Au coater after Au coating for 4 minutes.
The polished ice embedded in an epoxy disk was set to the cryo-holder and transferred to cryo-stage (–190 °C) of Cameca ims-1270 instrument using cryo-transfer system . The liquid nitrogen was supplied by a roots pump to reduce the sample stage vibration. The measurement methods for oxygen isotopes were similar to those of .
We obtained mass spectra of oxygen isotopes from H2O-ice. Intensity of 16O peak was about 2.8 × 105 cps and a tale was observed symmetrically at both side of the peak below 3 cps. The interference of tail from 16OH– to 17O– was estimated to be about 10 ‰ because the intensity of 16OH– is comparable to 16O peak. Oxygen isotope analysis using 16OH- and 17,18OH- signal would be effective for further high precision oxygen isotope analysis for H2O ice as well as the tail correction method used in .
References:  Zolensky M. et al. (1999) Science, 285, 1377-1379.  Yurimoto H. et al. (2014) Geochem. J, 48, 549-56.  A. Ishibashi (2014) Master thesis  J. Song (2017) Master thesis.