Fast and Complete CO₂-to-Graphite Conversion for¹⁴C Accelerator Mass Spectrometry

Abstract

With Fe powder as a catalyst, CO 2 is completely converted to graphite within 90 minutes. The reaction proceeds at 650°C with an excess of H 2 . The reaction rate is enlarged by forced circulation and by keeping the water vapor pressure very low. The graphite samples obtained, consisting of 5mg of carbon, almost immediately produce stable 12 C − currents of the order of 20–30μA in the sputter source of a Van de Graaff accelerator. The currents can be maintained for at least 10 hours and are comparable to those from commercial graphite. No memory effects in the preparation system have been observed.