In our recent investigation of the IR spectrum of CO physically adsorbed on C60 films, two well-resolved absorption bands at 2135 and 2128 cm -1 were found, suggesting that the molecule is adsorbed on two different sites. To determine the nature of these adsorption sites, calculations of adsorption potentials and spectral shifts for the CO/C60 system were performed. The calculations were done for the fcc (100), fcc ( 111) hcp (001), and hcp (111) surface planes. In the calculations the 6-exponential and the Lennard-Jones potentials were used. A number of adsorption sites were chosen. These included the void space between four, three, and two neighboring C60 molecules and the center of the hexagon and the pentagon on the C60 surface. The calculated potentials and spectral shifts clearly indicate that adsorption sites in the voids between the C60 molecules are energetically preferred over sites on top of single C60 molecules. Comparison is made between results obtained with the two potentials and with results obtained previously with the two other carbon allotropes: graphite and diamond.
The adsorption of CO and NO on c 6 0 is studied using the technique of IR spectroscopy. The IR spectra of CO show two absorption bands, which indicate the presence of two adsorption sites on the C,, surface. The IR spectra of NO show, in addition, a multiplicity in the two absorption bands, which indicates that NO is adsorbed in its dimer form on two sites. Large spectral shifts are observed on adsorption of both CO and NO on C60, demonstrating that the interaction of these gases with c 6 0 is relatively strong. of carbon. The differences in behavior were related to the structure Of c60. (1) Kroto, H. W.; Allaf, A. W.; Baln, S . P. Chem. Rev. 1991, 91, (2) Tsidoni, E.; Kozirovski, Y.; Folman, M.; Heidberg, J. J. Electron 1213-1235.Photoexcited triplet and photoinduced doublet states of Cm oriented in a nematic liquid crystal (LC) and toluene, were studied by time-domain EPR. The data indicate that in both matrices, 3Cm undergoes temperature dependent molecular rotation. However, whereas in the LC the rotation rate is increased monotonously between 7 and 298 K, the dynamics in toluene depends strongly on its phase diagram. About the melting point of toluene, a polarized doublet is observed concurrently with the disappearance of the triplet. At higher temperatures, where the liquid phase prevails, the dynamics of the photoinduced doublet suggests an unpaired electron delocalized on an aggregate of CM in toluene, with relatively long-lived magnetization of -25 MS.
Interfacial reactions of cobalt with differently doped Si0.8Ge0.2 layers epitaxially grown on silicon, during furnace annealing up to 600 °C, were compared. Undoped and highly boron- or antimony-doped Si0.8Ge0.2 strained layers were used for this study. The analytical tools employed were Auger electron spectroscopy, secondary ion mass spectroscopy, x-ray diffraction, and transmission electron microscopy. Both dopants accumulate at the surface as a result of the interfacial reaction with Co but boron also remains trapped between the reacted Co monosilicide region and a thin Co-rich near-surface layer. In addition, the boron-doped sample exhibits a large accumulation of Ge at the interface between the unreacted SiGe and the reacted monosilicide. The latter effect is related to the loss of Ge from the unreacted SiGe layers observed after high-temperature annealing, the B-doped SiGe epilayer undergoing the largest loss at 600 °C, while the Sb-doped epilayer was only slightly affected.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.