ACCUMULATION OF GOLD IONS ON A GOLD COATED QUARTZ CRYSTAL

摘要

A new experiment has been started to determine the atomic mass of gold in the unit kilogram. For this purpose, gold ions have to be accumulated to a weighable mass and the ion current has to be measured and integrated over the accumulation time. In a first accumulation experiment gold ions have been accumulated on a gold coated quartz crystal. A gold ion beam with a current of 5 μA and a range of ion energy between 25 eV and 300 eV has been used. As a result of the interaction of the gold ions with the surface of a gold coated quartz crystal, the ratio of the change of mass per time and the ion current multiplied with the elementary charge has been determined as a function of the ion energy. The transition between the mass loss and the mass increase at the oscillator quartz, mainly resulting from the sputtering effects, has been observed. The measurements have shown a reasonable agreement with the expected value of the mass of a gold atom in the unit kilogram for low ion energies.