Second generation laser-heated microfurnace for the preparation of microgram-sized graphite samples

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Date
2015-10-15
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Publisher
Elsevier
Abstract
We present construction details and test results for two second-generation laser-heated microfurnaces (LHF-II) used to prepare graphite samples for Accelerator Mass Spectrometry (AMS) at ANSTO. Based on systematic studies aimed at optimising the performance of our prototype laser-heated microfurnace (LHF-I) (Smith et al., 2007 [1]; Smith et al., 2010 [2,3]; Yang et al., 2014 [4]), we have designed the LHF-II to have the following features: (i) it has a small reactor volume of 0.25 mL allowing us to completely graphitise carbon dioxide samples containing as little as 2 μg of C, (ii) it can operate over a large pressure range (0–3 bar) and so has the capacity to graphitise CO2 samples containing up to 100 μg of C; (iii) it is compact, with three valves integrated into the microfurnace body, (iv) it is compatible with our new miniaturised conventional graphitisation furnaces (MCF), also designed for small samples, and shares a common vacuum system. Early tests have shown that the extraneous carbon added during graphitisation in each LHF-II is of the order of 0.05 μg, assuming 100 pMC activity, similar to that of the prototype unit. We use a ‘budget’ fibre packaged array for the diode laser with custom built focusing optics. The use of a new infrared (IR) thermometer with a short focal length has allowed us to decrease the height of the light-proof safety enclosure. These innovations have produced a cheaper and more compact device. As with the LHF-I, feedback control of the catalyst temperature and logging of the reaction parameters is managed by a LabVIEW interface. Crown Copyright © 2015 Published by Elsevier B.V.
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Keywords
Graphite, Graphitization, Aluminium, Carbon, Carbon dioxide, Accelerators, Vacuum furnaces, Mass spectroscopy
Citation
Yang, B., Smith, A. M., & Long, S. (2015). Second generation laser-heated microfurnace for the preparation of microgram-sized graphite samples. Paper presented to the AMS-13 the Thirteenth International Conference on Accelerator Mass Spectrometry, 24-29 August 2014, Aix en Provence, France. In Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 361, 363-371. doi:10.1016/j.nimb.2015.02.009