Surfaces play a critical role in many chemical processes such as energy conversion, environment cleaning, information processing, corrosion inhibition, bio-detection and bio-fingerprinting, etc. Information such as molecular identity, structure, orientation and nature of bonding of the surface adsorbed species may provide essential clues on the efficiency of these processes. The surface-enhanced Raman scattering effect, discovered in 1977, has been a valuable tool for surface and interfacial research. The enormous enhancement (a million times) associated with this process totally overcomes the low traditional low sensitivity problem in the normal Raman scattering. One of the specific applications is it makes detection of minute quantities of biochemical chemicals, e.g., DNA and RNA, on metal surfaces feasible for bio-detection and bio-fingerprinting. To improve sensitivity and detection limit, nanoparticle probes (of size nanometers or 10-9 meters) are being currently investigated. It is estimated that a detection limit of 10-14 molar concentration (less than 1 part per billion) can be achieved. Recently, Nanochemistry or .chemistry of the small world. has been an intense focus of research. The National Science Technology Council has made the National Nanotechnology Initiative (NNI) a top science and technology priority (www.nano.gov). For the year 2003, the U. S. government continues to fund $710 million for nanotechnoloy research and development through NNI, involving physics, chemistry, biology, materials science, and engineering. A new component of the 2003 Nanoscience and Engineering (NSE) program is the Nanotechnology in Undergraduate Education (NUE), with an emphasis on the .incorporation of undergraduate research opportunities based on nanoscience and engineering into curriculum at any level, particularly during first and second year studies.. The objective of this project is to combine surface-enhanced Raman scattering effect with nanotechnology to improve the detection limit and perhaps selectivity in bio-detection and bio- fingerprinting. Raman spectroscopic measurements will be performed on molecules adsorbed on nanoparticles (2-500 nanometers) on a EDUC Raman 633 spectrometer equipped with a He-Ne laser. The Ag and Cu colloids will be made according to an established procedure (Loo et. al, Chem. Phys. Lett. 297, 1998, 83-89). The silver and gold nanoparticles will be prepared according to Cao et. al (Science, 2003).

The first phase of study will involve diamides (urea, thiourea and selenourea), thioacetamides, and organonitriles (organic molecules with nitrile C=N functional groups) on colloids. The second phase of study will involve biochemical detection (e.g., DNA and RNA) on Ag and Au nanoparticles. The first phase of study is to investigate molecule-surface interactions. For example, organonitrile molecules have three bonding sites of bonding to metal surfaces, and the specific site of bonding can be distinguished from the Raman spectroscopic measurements. The wavenumber of the C=N group for an unadsorbed organonitrile molecule is about 2,250 cm-1. When the organonitrile molecule is bonded (or adsorbed) to metal surfaces in an end-on fashion via the lone-pair electrons on the N group (called the s-bonding), the C=N group wavenumber will increase to about 2,270 cm-1. When the molecules is adsorbed in a flat fashion via the p-electrons of the C=N group (the p-bonding), the C=N group wavenumber will decrease by 150 cm-1 to about 2,150 cm-1. When the molecule is adsorbed via both the C and N atoms of the C=N group (the ?(C,N) bonding), the CN group wavenumber will decrease by about 600 cm-1 to about 1,600 cm- 1. From the Raman spectroscopic measurements, one can tell the mode of bonding or adsorption of molecules to surfaces. There is a wealth of information on the metal complexes from which comparison with the molecule-surface interactions can be made.

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