Fast and Complete CO2-to-Graphite Conversion for 14C Accelerator Mass Spectrometry

Abstract

With Fe powder as a catalyst, CO2 is completely converted to graphite within 90 minutes. The reaction proceeds at 650 degrees C with an excess of H2. 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 12C- currents of the order of 20-30 micro-A 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.