Planar tunnel junctions were fabricated by self-assembling 1,1'- ferrocenedicarboxylic acid (FDCA) onto native oxides of thermally deposited aluminum films and subsequently depositing a second aluminum film. Junctions were characterized using Reflection-Absorption Fourier Transform Infrared Spectroscopy (RAIRS) and current-voltage (I-V) spectroscopy. Before deposition of the second aluminum film, RAIRS of FDCA and ferrocenecarboxylic acid (FCA) films revealed COO(-), C=O, and Fc ring stretching modes, indicating that both types of molecules can interact strongly with the oxide and remain intact. After deposition, systems exhibited prominent COO(-) modes and weakened C=O modes, indicating further reaction with aluminum/aluminum oxide. Fc ring modes persisted in FDCA systems but disappeared in FCA systems, suggesting that the second COOH group in the FDCA molecule can act as a protecting group for the ferrocene moiety. Cyclic I-V measurements of FDCA tunnel junction systems revealed very strong ( approximately 10-fold) hysteretic differential conductance switching that was both reversible and stable. Control measurements using as prepared junctions, as well as junctions containing 1,6-hexanedioic acid, 1,9-nonanedioic acid, 1,4-dibenzoic acid, or FCA revealed only very weak ( approximately 10%) differential conductance changes. We attribute FDCA junction switching to barrier profile modifications induced by oxidation/reduction of the functionally protected ferrocene moieties.

No abstract

Articles you may be interested inVibrational spectra of metal-molecule-metal junctions in electromigrated nanogap electrodes by inelastic electron tunneling Appl.

We describe a solution phase method to generate conjugated oligoazomethine assemblies on quartz and silicon oxide surfaces. The method is based on a controlled iminization reaction in which aromatic aldehydes and amines (1,4-terephthaldicarboxaldehyde, TPDA, and 1,4-phenylenediamine, PPDA) are sequentially assembled onto amino-functionalized substrates. Polarized attenuated total reflectance Fourier transform infrared spectroscopy and spectroscopic ellipsometry confirm monomer assembly on oxidized silicon surfaces. Using UV-visible spectroscopy with quartz substrates, we explored the roles of temperature, acid catalyst, and monomer concentration on rates of film formation. Arrhenius plots of observed rate constants yielded values for activation energies of 28 ( 7, 14 ( 7, and 17 ( 8 kJ mol -1 for uncatalyzed TPDA, catalyzed TPDA, and catalyzed PPDA assembly, respectively. Observed rate constants for TPDA assembly grew linearly with monomer concentration, while those for PPDA assembly were independent of monomer concentration. Fully formed films were found to be remarkably stable to repeated sonication and exposure to solvents at elevated temperatures.

Scientists constantly generate great ideas in the laboratory and, as most of us were meant to believe, we should publish or perish. After all, what use is a great scientific idea if it is not shared with the rest of the scientific community? What some scientists forget is that a good idea can be worth something - sometimes it can be worth a lot (of money)! What do you do if you believe that your idea has some commercial potential? How do you turn this idea into a business? This chapter gives the aspiring scientific entrepreneur some (hopefully) valuable advice on topics like choosing the right people for your management team, determining inventorship of the technology and ownership shares in the new company, protecting your intellectual property, and others; finally, it describes some of the various pitfalls you may encounter when commercializing an early stage technology and instructions on how to avoid them.