Ultrahigh vacuum cluster deposition source for spectroscopy with synchrotron radiation

Abstract

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 20pAmm−2–10nAmm−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.

Direct observation of high-spin states in manganese dimer and trimer cations by x-ray magnetic circular dichroism spectroscopy in an ion trap

“…40,42 This prepeak at the onset of 2p excitation of the free molecular ion is a sensitive measure of parallel 3d-4s spin alignment that vanishes upon cluster deposition. 40,42,[70][71][72] In conclusion, our results from XMCD spectroscopy provide the first direct experimental evidence for the 12 Σ + g ground state of free Mn + 2 ions, in agreement with electron spin resonance spectroscopy of Mn + 2 isolated in inert gas matrices 27,28 and in agreement with indirect evidence from photodissociation spectroscopy of free Mn + 2 ions. 29 High spin coupling and chemical bonding in cationic Mn + 2 are in strong contrast to the 1 Σ + g ground state of the neutral Mn 2 van der Waals molecule.…”

Hybridization and magnetism in small FePt alloy clusters

“…Figure 1 shows the mass spectra of the clusters up to Pt 3 , produced from the FePt target. A more detailed description of the cluster source and its capabilities are given in [12].…”

Size-dependent properties of small deposited chromium clusters by x-ray absorption spectroscopy

“…15 Clusters are generated by ion bombardment of a high purity chromium target ͑Goodfellow, 99.98%͒ with 30 keV xenon ions. The cluster formation process takes place in high vacuum at a base pressure of 1 ϫ 10 −8 mbar.…”