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|Title: ||A first step toward small-mass AMS radiocarbon analysis at Nagoya University|
|Authors: ||Minami, M|
|Issue Date: ||22-Mar-2010|
|Citation: ||Minami, M., Miyata, Y., Nakamura, T., Hua, Q., (2011). A first step toward small-mass AMS radiocarbon analysis at Nagoya University. 12th International Conference on Accelerator Mass Spectrometry (AMS 12), 20th - 25th March 2011. Museum of New Zealand: Te Papa Tongarewa, Wellington, New Zealand.|
|Abstract: ||We have started to establish a small-mass sample preparation system at Nagoya University. In the
first step, NIST Ox-II standard samples <0.5 mgC, graphitized using our regular sample
preparation protocol, were measured for 14C. The 14C/12C ratios of these small-mass samples were
affected by the decrease in beam current intensity and incomplete graphitization especially for
samples <0.3 mgC.
In the second step, we have designed a compact graphitization system suitable for small-mass
samples and compared its performance to that of our regular graphitization system. During the
graphitization reaction following our regular protocol, by-product water vapor was incompletely
trapped, which resulted in low graphite yield or no graphitization for samples of <0.5 mgC.
Meanwhile graphite was successfully produced for samples of 0.2mgC using the new reactor. The
SEM images of small-samples using the new reactor show spotted graphite covering the spherical
iron particles. No or very little graphite was observed for the samples graphitized using our regular
graphitization system. During the graphitization reaction using the sealed tube method, water
vapor was incompletely trapped, which resulted in low graphite yield especially for samples of <0.5
mgC. Meanwhile graphite was successfully produced for samples of 0.2mgC using the new reactor.
The cold trap at −80°C employed in the new graphitization system was effective in trapping water
for small-mass samples. The combination of lower temperature for trapping water and a reduction
in reactor volume delivered higher graphitization efficiency for small samples. We are now ready
for 14C analysis of samples of around 0.2mgC.
We also report an example of stepwise combustion of samples containing sulfur in a closed tube to
produce graphite successfully. Copyright (c) 2010 AMS12|
|Appears in Collections:||Conference Publications|
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