A cold finger cooling system for the efficient graphitisation of microgram-sized carbon samples
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- 作者：Bin Yang ; bin.yang@ansto.gov.au ; A.M. Smith ; Quan Hua
- 关键词：Accelerator mass spectrometry ; Radiocarbon ; Graphitisation ; Water trap ; Cold finger ; Cooling system ; Laser-heated microfurnace ; Bosch reaction
- 刊名：Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
- 出版年：2013
- 出版时间：January, 2013
- 年：2013
- 卷：294
- 期：Complete
- 页码：262-265
- 全文大小：678 K
文摘
At ANSTO, we use the Bosch reaction to convert sample CO2 to graphite for production of our radiocarbon AMS targets. Key to the efficient graphitisation of ultra-small samples are the type of iron catalyst used and the effective trapping of water vapour during the reaction. Here we report a simple liquid nitrogen cooling system that enables us to rapidly adjust the temperature of the cold finger in our laser-heated microfurnace. This has led to an improvement in the graphitisation of microgram-sized carbon samples. This simple system uses modest amounts of liquid nitrogen (typically <200 mL/h during graphitisation) and is compact and reliable. We have used it to produce over 120 AMS targets containing between 5 and 20 ¦Ìg of carbon, with conversion efficiencies for 5 ¦Ìg targets ranging from 80 % to 100 % . In addition, this cooling system has been adapted for use with our conventional graphitisation reactors and has also improved their performance.