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Interaction Between Molecule And Metal Probed By Vibrational Spectroscopy

Posted on:2007-11-03Degree:DoctorType:Dissertation
Country:ChinaCandidate:G K LiuFull Text:PDF
GTID:1101360212477752Subject:Physical chemistry
Abstract/Summary:PDF Full Text Request
With a development of nearly three decades, surface-enhanced Raman spectroscopy (SERS) has become one of the most important in-situ spectroscopies and plays important role in interfacial electrochemistry. However, up to now, most of the research are still limited to three noble metals: Au, Ag and Cu with high SERS activity and the classical SERS probe molecules including pyridine, pyrazine with high surface sensitivity. Furthermore, charge transfer mechanism in SERS is still unclear. In order to develop SERS into a general surface spectroscopy, one shall be able to overcome the abovementioned difficulties. Therefore, the main results of present dissertation are divided into two parts1. Extending research area of SERSDue to the very weak SERS signals from the molecules, including benzene, toluene and acetylene that tend to be adsorbed on transition metal surfaces in a parallel adsorption configuration, there are very limit reports on such systems. Through the optimizations of the sensitivity of Raman instrument and the roughening procedure of metal surfaces, the SERS signals of these molecules have been obtained on Pt, Ru, Rh and Pd surfaces successfully. Systematic study of the electrochemical adsorption behaviors of these molecules has been carried out. The chemical and physical coadsorption of benzene with halide ions and the electrochemical polymerization of acetylene have been studied systematically at the molecular and electronic structural levels.2. Exploring charge transfer mechanism related to SERS process.By taking advantage of femto-second time resolution of ultrafast-IR spectroscopy, the charge transfer and energy transfer between metal and molecules have been preliminarily studied. ReC0 molecule modified Au NPs have been investigated. The distance between ReC0 and Au NPs core was changed by using thiols with different lengths as bridge. When the ReCO molecules are anchored to the Au NPs surface through the conjucated benzene right, there may exist the charge transfer between ReCO and Au NPs related to SERS process. When the ReCO molecules are adsorbed on the Au NPs surface via the non-conjugated alkane group, the rates of charge transfer and energy transfer between ReC0 and Au NPs will decrease with the increasing length of the alkane chain. This observation has been verified by...
Keywords/Search Tags:Surface-enhance Raman spectroscopy, Electrochemical adsorption, Charge transfer, Ultrafast IR spectroscopy, Transition metal
PDF Full Text Request
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