PERFORMANCE OF THE VUV BEAMLINE-4.1 AT THE SRS, DARESBURY LABORATORY

The performance of a recently commissioned beamline, designated BL4.1, at the SRS, Daresbury Laboratory, is described. This beamline covers the energy range 15 greater than or equal to hv greater than or equal to 200 eV, using a spherical grating monochromator, and is equipped wi th a UHV surface-science endstation containing a Scienta SES200 and an HA54 angle-resolving electron-energy analyser. Design parameters and optical specifications are tabulated. Monochromator resolution has bee n determined by measuring the Fermi edge of a Pt foil cooled to 40 K a nd these values are compared with the calculated resolution. The flux delivered to the endstation has been measured directly using a calibra ted photodiode. The performance of the beamline is further illustrated by reference to a study of the angular distribution of photoemitted i ntensity from a band-gap state on a TiO2(110) 1 x 2 surface.