Ultrahigh vacuum cluster deposition source for spectroscopy with synchrotron radiation

A versatile cluster source has been developed for the deposition and investigation of mass selected metal clusters on single crystal substrates under ultrahigh vacuum conditions. The cluster deposition experiment is designed for spectroscopy with synchrotron radiation to probe the properties of mass selected clusters in x-ray absorption, x-ray magnetic circular dichroism, and x-ray photoelectron spectroscopy. The experimental setup consists of three stages, and is based on a sputter source for cluster production, a magnetic dipole field for mass selection, and an ultrahigh vacuum chamber for cluster deposition. With this cluster source, metal clusters of up to 40 atoms per cluster can be produced, mass separated and deposited onto a substrate. In this size range, cluster current densities of 20 pA mm − 2 – 10 nA mm − 2 have been determined experimentally, depending on cluster material and size. For substrate preparation, the experimental chamber is fully equipped with standard surface science tools. Cluster yields are presented for a variety of sputter targets. The capability to produce truly size-selected clusters is demonstrated with mass spectra.