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

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS

卷:361

Article; Proceedings Paper

Macario, Kita D.¹  Oliveira, Fabiana M.¹  Carvalho, Carla²  Santos, Guaciara M.³  Xu, Xiaomei³  Chanca, Ingrid S.¹  Alves, Eduardo Q.¹  Jou, Renata M.¹  Oliveira, Maria Isabela¹  Pereira, Bruna B.¹  Moreira, Vinicius¹  Muniz, Marcelo C.¹  Linares, Roberto¹  Silveira Gomes, Paulo Roberto¹  dos Anjos, Roberto Meigikos¹  Castro, Maikel D.^1,4  dos Anjos, Leandro²  Marques, Aguinaldo N.⁵  Rodrigues, Luiz Frederico^1,6 

[1] Univ Fed Fluminense, Inst Fis, Dept Fis, BR-24210346 Niteroi, RJ, Brazil

[2] Univ Fed Fluminense, Inst Quim, Dept Geoquim, BR-24020150 Niteroi, RJ, Brazil

[3] Univ Calif Irvine, Dept Earth Syst Sci, Irvine, CA 92697 USA

[4] Inst Super Tecnol & Ciencias Aplicadas, Havana 10400, Cuba

[5] Outeiro Sao Joao Batista, Inst Biol, Dept Biol Marinha, BR-24001970 Niteroi, RJ, Brazil

[6] Inst Petr & Recursos Minerals, BR-90619900 Porto Alegre, RS, Brazil

关键词: Sample preparation;    Graphitization;    Isotopic fractionation;    Reaction temperature;   

DOI  :  10.1016/j.nimb.2015.03.081

来源: Elsevier

【 摘 要 】

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. (C) 2015 Elsevier B.V. All rights reserved.

【 授权许可】

Free