Published online by Cambridge University Press: 15 February 2011
Helium decorated vacancies may be trapped to a high degree and with a high activation enthalpy at impurities in metals. This effect is studied by means of the hyperfine interaction of the radio-active impurities 111In → 111Cd, 119Sb → 119Sn and 129mTe → 129I, implanted into a number of f.c.c. metals and into iron and cobalt. Large changes of the magnetic hyperfine field are caused at 119Sn impurities in Ni, Co and Fe and hiqh values of the electric quadrupole interaction strength are found at 111Cd impurities in Al, Cu, Ag, Ni and Pt when helium decorated vacancies are trapped at the impurities. These effects provide a new method for studying the trapping and desorption mechanism of helium in metals.