isused to carry out the experiments. All measurements wereperformed at room temperature. Neon (Linde Gas, >99.999%) isoffered via backfilling the chamber using a bakeable leak valve.The gas line is evacuated and can be heated in order to ensurecleanness. A quadrupole mass spectrometer with electron impactionization and an electron multiplier (Balzers QMS 112 A) is usedto analyse the gas composition with an overall integration time of30s per data point. During measurements, the partial pressure ofthe analysed neon gas has been chosen to be about 100 timesas big as the total pressure of the residual gas. Additionally, aspectrum of the residual gas before neon dosage has beensubtracted from the neon spectrum. All peak positions have beencorrected according to the literature values of helium and oxygen.