LARGE SOLID ANGLE X-RAY PHOTOELECTRON INTENSITY DISTRIBUTIONS FROM CO, METHOXY, AND FORMATE ADSORBED ON NI(110)

Adsorbed layers of CO, methoxy (CH3O) and formate (HCOO) on a clean Ni (110) surface are investigated by angle-resolved X-ray photoelectron s pectroscopy. Large solid angle stereographic projections of C 1s or O 1s core level intensity measured for these adsorbates at 85 K show str ong forward scattering enhancements that unambiguously and rather dire ctly determine the molecular orientation, and in the case of CO, the o rder within the layer. CO in the (2 x 1) p2mg structure and methoxy ar e tilted by 20 degrees and 30 degrees relative to the normal, respecti vely, with the projection of the tilt in the [001] azimuth. Formate is bonded through oxygen in the bidendate configuration, aligned along t he [110] azimuth; The O-C-O bond angle is determined as 124 degrees. T hese results are in good agreement with previous data. (C) 1998 Elsevi er Science B.V. All rights reserved.