Chemistry with a tiny hammer - cleaving the C-H bonds of adsorbed organic molecules with hyperthermal protons

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This proposal aims at exploring my concept of performing chemistry with a tiny hammer - a hyperthermal proton, for the synthesis of novel polymer films.  Recently my research team showed that when adsorbed hydrocarbon molecules are bombarded by 10eV protons, the energy transfer is effective in H-H collisions but ineffective in H-C collisions.  Such a difference in kinematics leads to the cleavage of C-H bonds with no C-C bond breakage.  The adsorbed hydrocarbon molecules are thereby cross-linked into an ultrathin polymer film.  In the next five years, we will further clarify the nature and reaction mechanisms of this method and its scope of applicability towards the production of novel polymer films having tailor-made physical and chemical properties.  To study the reaction mechanisms, we will analyze species emitted from adsorbed precursor molecules during ion bombardment as a function of ion energy and ion type (H+, D+, and He+).  We will compare these data with those collected from surface analysis of the bombarded samples.  To explore the applications of the proposed hyperthermal proton method, we will use it to cleave C-H bonds of conjugated semiconducting polymer films and thereby to increase the average conjugated chain length with the induced cross-linking.  Normally as-deposited conjugated polymer films are thermally cured to increase cross-linking and electrical conductivity. The proposed proton treatment provides an attractive alternative as it is a dry process with no heating requirement.  In addition to this application, we will use the method to cross-link unsaturated and aromatic organosilane self-assembly monolayers on conductive substrates such as n-TiO2, for the development of molecular electronics.   We have already paved the ground work and confirmed the feasibility of our proposed approaches. Therefore, we are confident that if the proposed project is approved, we will produce original results bearing both scientific and technological impacts, and train highly qualified personnel in this market-driven field.