ATOMIC RELEASE OF HYDROGEN FROM PURE AND BORONIZED GRAPHITES

The release of implanted hydrogen from pure and boronized graphites was investigated with reemission and thermal desorption (TDS) experiments. In both experiments the release of hydrogen atoms is observed. At low temperatures the release of hydrogen occurs only in the form of molecules. Above temperatures of about 900-1100 K an increasing fraction of the implanted hydrogen is released as atoms. For pure graphite, the reemission of hydrogen atoms starts at about 900 K, whereas the onset of the atomic remission is shifted to higher temperature for the boronized graphite. In the TDS experiments the release of hydrogen molecules peaks around 1000 K, the release of atomic hydrogen around 1100-1200 K. From a comparison of the reemission with the TDS data the conclusion is drawn, that the atomic release of hydrogen from graphite after hydrogen implantation is a thermal process.