F. Zaera
Sep 2, 1991
Citations
0
Influential Citations
31
Citations
Journal
Surface Science
Abstract
Abstract The surface chemistry of iron pentacarbonyl on Pt(111) was studied using reflection-absorption infrared spectroscopy (RAIRS). A small amount of molecular adsorption is observed below half saturation at 110 K., but about 70% of the iron pentacarbonyl decomposes upon chemisorption to yield atomic iron and coadsorbed carbon monoxide. Deposition at 275 K, on the other hand, results in total decomposition and in a steady state growth of iron films on the surface; only CO bonded directly to platinum atoms is seen by RAIRS. The molecular adsorption of iron pentacarbonyl is proposed to occur with a concomitant change of geometry from a trigonal bipyramid to a square pyramid as suggested by the high frequency value observed for the CO mode, around 2060 cm −1 . Annealing the surface to 185 K after exposures at 120 K results in desorption of the condensed multilayer and in decarbonylation of the remaining molecules to form iron tetracarbonyl, which displays a peak in the RAIRS spectrum at 2035 cm −1 . Further heating to 240 K yields two new bands at 1980 and 1935 cm −1 , which we assign to Fe(CO) 3 . Both Fe(CO) 4 and Fe(CO) 3 desorb as iron pentacarbonyl after recombination with CO at 195 and 265 K, respectively.