STRUCTURE DETERMINATION OF ORDERED 1 3-MONOLAYER PB ON GE(111) BY PHOTOELECTRON HOLOGRAPHY/

The technique of photoelectron holography has been applied to the (roo t 3x root 3)R30 degrees phase of 1/3-monolayer Pb on Ge(111) for a det ermination of the local bonding structure of the Pb adatom. Angle-reso lved photoemission from the Pb 5d core level shows intensity oscillati ons as a function of photon energy due to diffraction effects. These o scillations were measured at various emission angles and Fourier inver ted to yield three-dimensional real-space images of the nearest neighb ours to the Pb emitter atom, which is bonded at the T-4 site. The use of the small-cone technique to eliminate artifacts is discussed.