Adsorbate-geometry specific subsurface relaxation in the CO/Pt(111) system.
A dramatic multilayer substrate relaxation is observed for the (square root 19 x square root 19)-13CO adlayer phase on a Pt(111) electrode by surface X-ray scattering. Within the (square root 19 x square root 19) unit cell, a vertical expansion of 0.28 A was determined for the Pt atoms under near-top-site CO molecules, whereas only 0.04 A was found under near-bridge-site CO molecules. The lateral displacements involve small rotations toward more symmetric bonding. Both the expansions and rotations extend into the bulk with a decay length of 1.8 Pt layers. This nonuniform layer expansion, hitherto unseen, appears to be a manifestation of the differential stress induced by CO adsorption at different sites.
Wang
J X
JX
Robinson
I K
IK
Ocko
B M
BM
Adzic
R R
RR
D000327:Adsorption; D002248:Carbon Monoxide / Q000737:chemistry*; D004566:Electrodes; D010984:Platinum / Q000737:chemistry*; D012542:Scattering, Radiation; D013499:Surface Properties; D014965:X-Rays
D010984:Platinum; D002248:Carbon Monoxide