Tungsten oxide (WO x) films grown on tungsten (W) are characterized by depth-resolved Doppler-broadening spectroscopy (DBS) and positron-annihilation lifetime spectroscopy (PALS) as primary analytical methods. The WO x films are prepared on W (111) monocrystals using either exposure to air, electrochemical, or thermal oxidation procedures, chosen according to the desired thickness. We calculate the lifetime of positrons in the bulk of WO x and in different types of vacancies using the atomic superposition (AtSup) method. These give the size required for a multivacancy in WO x needed for it to be identifiable by PALS. In our experiments, we identified a distinct positron lifetime of 325 p s in the thin oxide layer on W exposed to air. This value overlaps with that of multivacancy sites in W and, hence, should be taken into account in future PALS studies of radiation-induced defects in W.
Tungsten oxide (WO x) films grown on tungsten (W) are characterized by depth-resolved Doppler-broadening spectroscopy (DBS) and positron-annihilation lifetime spectroscopy (PALS) as primary analytical methods. The WO x films are prepared on W (111) monocrystals using either exposure to air, electrochemical, or thermal oxidation procedures, chosen according to the desired thickness. We calculate the lifetime of positrons in the bulk of WO x and in different types of vacancies using the atomic superposition (AtSup) method. These give the size required for a multivacancy in WO x needed for it to be identifiable by PALS. In our experiments, we identified a distinct positron lifetime of 325 p s in the thin oxide layer on W exposed to air. This value overlaps with that of multivacancy sites in W and, hence, should be taken into account in future PALS studies of radiation-induced defects in W.
