Advances in the graphitization protocol at the Radiocarbon Laboratory of the Universidade Federal Fluminense (LAC-UFF) in Brazil

作者：Macario Kita D^*; Oliveira Fabiana M; Carvalho Carla; Santos Guaciara M; Xu Xiaomei; Chanca Ingrid S; Alves Eduardo Q; Jou Renata M; Oliveira Maria Isabela; Pereira Bruna B; Moreira Vinicius; Muniz Marcelo C; Linares Roberto; Silveira Gomes Paulo Roberto; dos Anjos Roberto Meigikos; Castro Maikel D; dos Anjos Leandro; Marques Aguinaldo N; Rodrigues Luiz Frederico

来源：Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms , 2015, 361: 402-405.

DOI：10.1016/j.nimb.2015.03.081

• Sample preparation
• Graphitization
• Isotopic fractionation
• Reaction temperature

In this paper, we summarize the sample preparation methods currently used at the Radiocarbon Laboratory of the Universidade Federal Fluminense (LAC-UFF) in Brazil. We also report on a series of results with regards to the graphitization protocol. Tests with different temperatures and baking times were performed, and carbon stable isotope ratios of graphite were measured by an EA-IRMS (elemental analyzer coupled with an isotopic ratio mass spectrometer) to infer the completeness of the graphitization reaction. We monitored the muffle furnace temperature using an independent thermocouple and found a -60 degrees C offset, which may have caused the lower graphitization yields (detected from the large isotopic fractionation on several reference materials targets). At a temperature of 520 degrees C, the isotopic fractionation in the graphitization reaction was systematically lower (-5 parts per thousand in average) and the overall scattering was reduced. As long as isotopic fractionation corrections are made using the online stable isotopes ratios provided by the AMS system, the accuracy of the C-14 results should be maintained.

• 出版日期2015-10-15