D. J. Frankel

Study of dissociation of water on Ge(100) by high-resolution electron-energy-loss spectroscopy

Abstract High-resolution electron energy loss spectroscopy has been used to study the interaction of the clean Ge(100) surface with water under ultrahigh vacuum conditions. We observe no detectable molecular adsorption nor dissociation at room temperature up to 100 L water exposure. At 100 K both molecular and dissociated water are present on the surface even for 0.1 L exposure. Vibrational modes of the hydroxyl group have been identified by observing the isotopic shift between the H 2 O and D 2 O energy loss spectra. Dissociation and desorption of water have been studied in the 100–620 K range. The data show that at room temperature and above water is completely dissociated into H and OH. At higher temperatures (> 450 K) the OH radical also starts to dissociate, leaving oxygen and hydrogen bonded to Ge. Upon annealing to 620 K only atomic oxygen is detectable on the surface.

A deoxygenation process on cleaved Si

Abstract We found that cleaved Si surfaces play a catalytic role in stimulating a deoxygenation process in furan. A detailed experimental study of this phenomenon was performed with surface vibrational spectroscopy and with photoemission spectroscopy. This discovery expands the range of known catalytic phenomena involving organic molecules on cleaved silicon, and their practical interest.

Surface vibrational study of acetylene adsorption on cleaved silicon

Abstract The adsorption of acetylene on cleaved silicon is nondissociative and exhibits similarities with the adsorption of ethylene on the same surface. These similarities strengthen the hypothesis that the Si surface is a good π-donor.

Neopentane on cleaved Si: Vibrational study of the adsorption of a highly symmetric hydrocarbon

Abstract We used high-resolution electron energy loss spectroscopy to investigate the adsorption properties of neopentane on cleaved Si(111). The results obtained on room-temperature substrates are consistent with the hypothesis of a dissociative reaction involving the breaking of CC bonds. Therefore, CC bond breaking can be included among the many reactions involving organic molecules that are catalyzed by cleaved silicon

Surface Vibrational Studies of Organic-Molecule Chemisorption on Silicon

Abstract We discuss the most interesting results of an extensive research program on the chemisorption properties of organic molecules on semiconductor substrates. Specific systems discussed in detail are benzene, pyridine and thiophene on cleaved Si(111). In particular, we find that the chemisorption of benzene or pyridine on room-temperature substrates leads to the breaking of C-H bonds in the absorbed molecules and to the formation of Si-C bonds.

Surface Vibrational Studies of Chemisorption on Silicon

Surface-sensitive experimental probes have been extensively used in recent years to study chemisorption processes on semiconductor surfaces and in particular their role in the formation of metal-semiconductor and heterojunction interfaces.1 There has been, however, very limited use of one of the most powerful surface physics techniques — high-resolution electron energy loss spectroscopy (HREELS). We present here the results of two HREELS studies of chemisorption on annealed Si(111)7x7. Besides their intrinsic interest, these results also demonstrate the power of HREELS in studying semiconductor interface formation processes.