Magnetic properties of surface outermost layrs and adlayrs studied by a spin-polarized metastable-atom beam

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This project has animed at developing a beam source of helium metastable atoms polarized in electronic spin and at applying the source to the analysis of the spin state in surface outermost layrs. The research has progressed behind schedule because of a head-investigator's change of post. In the last year of the project term, we have performed an experiment of spin polarization of metastables as well as a study on the surface electronic using an established metastable deexciation spectroscopy (MDS) Apparatus.(1) We have constructed a source having an excitation chamber equipped with a hollow cathode and a skimmer together with an optical pumping unit for spin polarization. For the latter, circular-polarized photons have been created by passing He discharge light through a linear polarizer and a lambda/4 plate.(2) The electronic structure of Cs plus oxygen co-adsorbed layrs on the Ge (100) surface has been studied by MDS using a 2^3S He^* beam, mainly concerning Cs 6s, O 2p states and DELTA F.It is shown in the MDS spectra that the degree of electron transfer from adsorbed Cs 6s to incoming oxygen at the Ge (001) surface remains incomplete in contrast to a complete charge outflow from the Cs 6s orbitals to oxygen at the Si (001) surface. we have demonstrated by the whole experiment in this project that the MDS can extract very sensitively local density of states at surface outermost layrs.