Trap mutation in He-doped ion-implanted tungsten

In this work, we report on an investigation of the defect complexes InVe(2)He(n) in tungsten by means of PAC. The release steps InVe(2)He(n), --> InV2Hen-1 + He were identified for n = 1-5. The dissociation energies, in the range of 2.9-4.5 eV, agree perfectly with the values that have been previously determined by means of THDS. The quadrupole frequency is about 122 Mrad/s for n = 1,2 and about 101 Mrad/s for n = 3,4. These values are smaller than the frequency of the undecorated vacancy (n = 0). The vacancy mutates into a divacancy if it is filled with about 10 He atoms, giving rise to a quadrupole frequency of about 218 Mrad/s. This so-called ''trap mutation'' ultimately leads to bubble information. We observed at least three different bubble-associated quadrupole interactions.