Tritium release from Li 2O studied by infrared absorption spectroscopy

Abstract

Desorption of a surface hydroxyl group of -OD on Li 2O into the sweep gas of dry Ar, Ar+H 2 or Ar+H 2O was studied by using a diffuse reflectance method with Fourier transform infrared absorption spectroscopy under controlled H 2O (D 2O) or H 2 (D 2) partial pressure. Under a D 2O containing atmosphere, multiple peaks due to surface -ODs were observed in the O-D stretching vibration region and they showed different dependencies on temperature or D 2O vapor pressure. The surface -OD observed at 2660 and 2520 cm −1 was removed by drying under Ar gas at 833 K. However, surface -OD at 2900, 2540 and 2490 cm −1 stayed on the Li 2O surface up to 973 K. In order to remove these -ODs at 833 K, addition of H 2 to the sweep gas was needed. It was also found that desorption of surface -OD was affected by the oxygen partial pressure near the surface. We also compared the observed results with those of in situ tritium release experiments (TTTEx).