Bridging the pressure gap in surface science at the atomic level: H/Cu(110)

The structural response of the Cu(110) surface to H-2 gas pressures ranging from 10(-13) to 1 bar is studied using a novel high-pressure scanning tunn eling microscope (HP-STM). We find that at H-2 pressures larger than 2 mbar the Cu(110) surface reconstructs into the (1 X 2) "missing-row" structure. From a quantitative analysis of the pressure dependence of the surface rec onstruction, we conclude that Cu(110) responds identically to hydrogen at u ltrahigh vacuum conditions and at atmospheric pressures. From the HP-STM da ta, we extract refined values for the adsorption and desorption rate consta nts.