The fabrication of electronic devices based on organic materials has been investigated for possible use in memory devices (1), in molecular based transistors (2), as wiring (3), and for the fabrication of p-n junctions (4).In particular, organic electronically conducting polymers, e.g., polyaniline, polypyrrole and polythiophene (5,6) are important as materials for such applications, because these polymers can be formed electrochemically and show conductivities that depend on their state of charge. We describe here a method for the high resolution deposition of polyaniline on a Pt substrate based on an apparatus similar to the scanning tunneling microscope (STM). The STM has been used not only to determine surface topography and structure at the atomic level (7,8). but also to modify surfaces and for submicron lithography (9-13). Research in this laboratory recently has led to the development of a method for the high resolution deposition of metals with line widths better than 0.5 p.m in thin polymer films (14,15). The principle behind the technique is illustrated in Figure 1. This technique is based on the scanning electrochemical microscope (SECM) (16), which maintains a constant faradaic current between a tip electrode and a metal substrate electrode.In this case these electrodes are separated by a thin layer of an ionically conductive polymer, which serves as the electrolyte and contains cations that are free to move within the polymer matrix. The Nation ( 17) film thus provides an ionically conductive pathway for the current between the substrate and the tip and thus removes the need to use any liquid electrolyte solution. The current is driven by applying a potential between the tip and the metal.The apparatus used and the methods of tip preparation (platinum or tungsten) have been described previously (14,15). The sample was made by first vacuum sputtering Cr (ca. 50 A) then Pt (ca. 2 p.m) onto the surface of a glass slide. Nation films were prepared using a 1% w/w solution in ethanol. Drops of this were spin-coated at 3800 rpm onto the Pt surface. The final Nation film thicknesses were approximately 0.1 I~m. The sample was soaked in 0.1 M anilinium sulfate solution (prepared from Millipore water) for 40 min.There are several reasons for using protonated aniline. First, cations can be readily incorporated into Nation films via ion exchange.Second, electroactive polyaniline is formed in water only from acidic solutions, e.g., with aniline and H2SO 4 or HCIO4 (18). Third, the
ChemInform Abstract Irradiation of the dimeric title complex (I) in the presence of CCl4 or Mn2(CO)10 gives the mononuclear compounds (II) or (IV). These results indicate that long wavelength excitation of (I) results mainly in formation of (indenyl)Fe(CO)2 in fluid solution. In the absence of added ligands irradiation of (I) in hydrocarbon solution results in slow decomposition. However, when the irradiation is carried out in hydrocarbon solvents containing ligands L, IR and EPR data show that the (indenyl)Fe(CO)2 radical can be trapped. The resulting adducts react thermally to regenerate the starting compound (I). The photogenerated radicals in the presence of L are formulated as (V). The odd e-is Fe-located.
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