Evaporated gold island films have been the subject of studies dealing with a variety of spectroscopic and sensing applications. Development of these and other applications requires film stability as well as tunability of the morphology and optical properties of the island films. In the present work, ultrathin, island-type gold films were prepared by evaporation of 1.0-15.0 nm (nominal thickness) gold at a rate of 0.005-0.012 nm s -1 onto glass substrates modified with 3-mercaptopropyl trimethoxysilane (MPTS), the latter used to improve the Au adhesion to the glass. The morphology of the films, either unannealed or annealed (20 h at 200 °C), was studied using atomic force microscopy (AFM) and high-resolution scanning electron microscopy (HR-SEM). The information provided by the two imaging techniques is complementary, giving a good estimate of the shape of the islands and its variation with film thickness and annealing. The optical properties of the films were examined using transmission UV-vis spectroscopy, showing a strong dependence of the localized Au surface plasmon (SP) band on the morphology of the island films. The imaging and spectroscopy indicate a gradual transition from isolated islands to a continuous film upon increasing the Au thickness.

Potential profiles across molecular layers are constructed by means of noncontact electrically stimulated photoelectron spectroscopy, probing for the first time the molecule-substrate interface potential and resolving local screening effects across inner phenyl groups.

A general approach is demonstrated for the formation of monolayers comprised of free-base and metalated Bacteriochlorophyll-based derivatives providing a new vehicle for studying photosynthetic motifs and chromophore thin-film interactions. Accessibility to covalent and self-assembled systems on conducting, semiconducting, and insulating substrates is realized utilizing identical molecular building blocks. The monolayers retain the optical features typical for the new systems in solution. Molecular organization of chromophore interaction motifs can be sequentially designed using preassembled building blocks in solution and expressed in the thin film optical properties. For instance, intramolecular pi-pi stacking is conserved for the dimeric Ni-based chromophores as deduced from the spectroscopic measurements of the monolayers and in solution.

Redox reactions play key roles in fundamental biological processes. The related spatial organization of donors and acceptors is assumed to undergo evolutionary optimization facilitating charge mobilization within the relevant biological context. Experimental information from submolecular functional sites is needed to understand the organization strategies and driving forces involved in the self-development of structure-function relationships. Here we exploit chemically resolved electrical measurements (CREM) to probe the atom-specific electrostatic potentials (ESPs) in artificial arrays of bacteriochlorophyll (BChl) derivatives that provide model systems for photoexcited (hot) electron donation and withdrawal. On the basis of computations we show that native BChl's in the photosynthetic reaction center (RC) self-assemble at their ground-state as aligned gates for functional charge transfer. The combined computational and experimental results further reveal how site-specific polarizability perpendicular to the molecular plane enhances the hot-electron transport. Maximal transport efficiency is predicted for a specific, ∼5 Å, distance above the center of the metalized BChl, which is in remarkably close agreement with the distance and mutual orientation of corresponding native cofactors. These findings provide new metrics and guidelines for analysis of biological redox centers and for designing charge mobilizing machines such as artificial photosynthesis.