T03_01

A compact laser ablation system with a diode laser for AMS ¹⁴C measurement

Minamitani F¹, Omori T², Yoneda M², Ozaki H², Yamazaki K²

¹Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Japan, ²The University Museum, The University of Tokyo, Bunkyo, Japan

We constructed a laser ablation (LA) system using a diode laser of organic materials for AMS ¹⁴C measurement. The LA system can extract CO₂ in amounts of ~0.4 mg of carbon, using a 5.5W diode laser from a maximum of 0.6 mm diameter spot area. The LA system was assessed using standard materials (IAEA-C1, IAEA-C2, and IAEA-C3) and applied to natural samples such as tree-ring and bone. For LA sampling of organic samples, which often results in incomplete combustion, tungsten (VI) oxide was used as an oxidant to enhance complete burning. Results from the measurement of standard materials showed that the value of δ¹³C agrees with book values. A low ¹⁴C background of 0.0004±0.003 F¹⁴C was obtained, and ¹⁴C values were well reproduced within errors. This system was applied to ¹⁴C mapping in organic tissues; for example, the detection of cosmic-ray events in annual rings and ¹⁴C uptake during bone growth.