Volume 115, Issue 11, 15 September 2001
Index of content:
Mapping the orientation of exciton transition dipoles along individual nanostructures of molecular J-aggregates115(2001); http://dx.doi.org/10.1063/1.1403005View Description Hide Description
Modulation of the polarization state of incident light in reflection microspectroscopy is used to study locally the orientations of excitontransitiondipole moments of fiberlike nanostructures of J-aggregates of pseudoisocyanine dyes. The lowest exciton state assumes a wide range of directions with respect to the long axis of the fibers, from parallel to perpendicular. This behavior is correlated with the onset of polariton-like character of the local reflectance spectra. The results imply that a new structural model has to be conceived to explain the observed phenomena.
115(2001); http://dx.doi.org/10.1063/1.1403006View Description Hide Description
A catalyst preparation by design is one of the ultimate goals in chemistry. The first step towards this goal is to understand the origin of reaction barriers. In this study, we have investigated several catalyticreactions on some transition metalsurfaces, using density functional theory. All the reaction barriers have been determined. By detailed analyses we obtain some insight into the reaction barrier. Each barrier is related to (i) the potential energy surface of reactants on the surface, (ii) the total chemisorption energy of reactants, and (iii) the metald orbital occupancy and the reactant valency.