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

• Published in: Fēnxī huàxué 2015-12, Vol.43 (12), p.1888-1894
• Main Authors: LONG, Tao, SHI, Jian, BAO, Ze-Min, Clement, Stephen WJ, ZHANG, Yu-Hai, TIAN, Di, LIU, Dun-Yi
• Format: Article
• Language: English
• Subjects: Apatite; Confidence; Constraining; High resolution; Oxygen isotopes; Shrimps; Surface roughness; Zircon
• ISSN: 0253-3820
• DOI: 10.1016/S1872-2040(15)60885-4

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 delta super(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 mu m. The internal precision of single spot of zircon delta super(18)O is better than 0.15ppt (1 sigma ), with external precision better than 0.5% (95% confidence); the internal precision of the single analysis of Carbonate delta super(18)O is better than 0.20ppt (1 sigma ), with external precision better than 0.6ppt (95% confidence). A secondary extraction structure of SIMION simulation model was established to decipher the physical mechanism of edge and X-Y effect in the oxygen isotopes analysis of zircon, apatite, calcium carbonate, etc, by sensitive high resolution ion microprobe (SHRIMP) IIe MC. The results indicated that the detection precision of delta super(18)O was improved 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 was less than 1 mu m.