N. Azumaa, T. Miyazakia, K. Fuekia, K. Ashidab, K. Watanabeb, K. Furukawac, S. Ohnoc
a Department of Synthetic Chemistry, Faculty of Engineering, Nagoya University, Chikusa-ku, Nagoya 464, Japan
b Tritium Research Center, Toyama University, Gofuku, Toyama 930, Japan
c Department of Chemistry, Japan Atomic Energy Research Institute, Tokai-mura, Ibaraki 319-11, Japan
When silica is irradiated by 80-keV D+ ions or RF plasma of D2 gas, deuterium is trapped in the silica forming Si-OD bonds. The deuterium, trapped as OD bonds, is desorbed from the silica upon heating to form some release products. The thermal detrapping process corresponds to decrease of OD bonds and was studied by measurement of infrared Fourier transform spectroscopy (FTIR). The release products HDO, D2O, HD, and D2 were measured by quadrupole mass spectroscopy (QMS). The detrapping and release processes of trapped deuterium were studied by simultaneous measurement of FTIR and QMS. Since the release spectra of HDO, D2O, HD, and/or D2 correspond to the decrease spectra of OD bonds, these release products are formed by thermal decomposition of OD bonds. The formation of water (HDO, D2O) and hydrogen (HD, D2) depends upon concentration of pre-existing OH bonds and deuterium injection methods (80-keV D+ implantation or RFD2 plasma irradiation).
Keywords: D+ implantation; D2 plasma; silica; thermal release