Grant: Discovery Grants Program - Individual

This proposal aims at further lifting the scientific understanding and technological impact of our research in novel chemistry induced by hyperthermal collision. Since 2004, we have shown with many examples that when adsorbed organic precursor molecules are bombarded by 5-10eV protons, generally only their C-H bonds are cleaved because the kinetic energy transfer is merely effective in H---H collisions. The recombination of the carbon radicals leads to cross-linking the molecules into a stable molecular network having the desirable chemical functionalities of the precursor. A "green" technology requiring little chemical reagents other than hydrogen is thus invented to produce a cross-linked molecular film with tailor-made properties for surface modification or membrane applications. In 2008, we successfully developed a production prototype reactor to show that neutral hyperthermal molecular hydrogen can be generated to replace protons, for surface modification of electrically insulating substrates such as polymers or biomaterials. Grafting molecules with desirable chemical/biochemical properties on a polymer in a large area (>300 cm2) with a high throughput (< 1 second of exposure time) has indeed been demonstrated. Technology commercialization is under way. To learn more about the basic science in this powerful technology of using kinematics to break C-H bonds, we will use CH3-Si(111) as our model sample to study the nature of the collision-induced reactions as a function of the energy and collision angle of hyperthermal hydrogen projectiles. We will use our scanning tunneling microscopes and high resolution electron energy loss spectrometer to study the surface chemical changes induced by the bombardment. To expand the scope of this novel kinematics-driven chemistry, we will use our high flux of hyperthermal hydrogen and inert gas to prepare practical quantities of fullerenes encapsulating these species, and compare the experimental results with our computation data. This new means of producing practical amounts of fullerene derivatives will significantly advance fullerene chemistry. One PDF and two graduate students will be trained per year.