Influence of Edge Effect and X-Y Effect on Measurement Precision in Sensitive High Resolution Ion Microprobe IIe MC Oxygen Isotopes Analysis

Abstract Sensitive high resolution ion microprobe (SHRIMP) IIe MC has been widely used in the oxygen isotopes analysis of zircon, apatite, calcium carbonate, etc. This study described the procedures for SHRIMP IIe MC high precision O-isotope analysis. We simulated the SHRIMP II secondary extraction system using SIMION and discussed the cause and influence factors of edge effect and X-Y effect in the oxygen isotopes analysis. Higher δ 18 O precision can be achieved by limiting O-isotope analysis positions to the central region about 10 mm in diameter of the sample mount and ensuring that the target surface roughness is less than 1 µm. The internal precision of single spot of zircon δ 18 O is better than 0.15‰ (1σ), with external precision better than 0.5% (95% confidence); the internal precision of the single analysis of Carbonate δ 18 O is better than 0.20‰ (1σ), with external precision better than 0.6‰ (95% confidence).