INTERACTION OF H2S WITH THE RU(001) SURFACE

The interaction of sulfur and H2S with Ru(001) was studied between 350 and 1500 K with LEED, UPS, AES and Thermal Desorption Spectroscopy. Exposure to H2S at 350 K results first in the formation of a (2 × 2) LEED pattern followed by a (√3 × √3)R30°. Further exposure results in a diffuse c(4 × 2) pattern which sharpens upon heating to 500 K. Quantitative AES indicates that these structures correspond to 1 4, 1 3, 1 2 sulfur atom per surface Ru atom, respectively. UPS indicates that H2S dissociates upon adsorption at 350 K over the entire coverage range. Work function and Thermal Desorption Measurements show that below 1 3 (S/Ru) at 350 K only sulfur is adsorbed, indicating that hydrogen from H2S recombines and desorbs during the adsorption of sulfur. At higher sulfur coverages hydrogen remains trapped on the surface, but UPS measurements show that the H2S is dissociated. AES and Thermal Desorption Measurements yield an initial heat of desorption for sulfur of 105 kcal/mole. At coverages approaching saturation, the heat of desorption decreases rapidly to 50 kcal/mole. © 1979.