Commissioning of surface chemistry end-station in BL23SU of SPring-8

An experimental apparatus for surface reaction research is now under commissioning as an end-station of a soft X-ray beamline, BL23SU, in the SPring-8. A supersonic molecular beam (SSMB) technique is applied to control the translationalenergy of incident molecules. Owing to keeping low pressure in vacuum chambers during molecular beam operation by differential-pumping systems, the suppression of gas diffusion into the beamline was suf®ciently achieved. The translationalenergy control and photoemission spectroscopic performance were checked by preliminary experiments concerning the silicon oxidation using a conventional X-ray source. The photoemission intensity from chemisorbed oxygen atoms on an Si(1 0 0) surface was enhanced with increasing the translational-energy of incident oxygen molecules up to 3 eV. # 2001 Elsevier Science B.V. All rights reserved.