Surface-enhanced Raman scattering and surface-enhanced hyper Raman scattering : a systematic study of various probing molecules on novel substrates
by Qunjian Huang
2 v. (xxviii, 875 leaves) : ill. ; 30 cm
The objective of this thesis is to develop the SEHRS and SERS on novel substrates and to explore their chemical/biological applications....[ Read more ]
The objective of this thesis is to develop the SEHRS and SERS on novel substrates and to explore their chemical/biological applications.
Chpater 1 briefly introduces the surface-enhanced Raman scattering and surface-enhanced hyper-Raman scattering.
Chapter 2 describes the preparation of silver, gold, and copper nanoparticles on smooth electrode surfaces. Chemically prepared nanoparticles show the more efficient SERS activity than electrochemically prepared nanoparticles. Chapter 6 studies the surface enhancement effect of silver nanoparticles-on-electrode settings in Raman and hyper-Raman scattering.
Chapter 3 and 4 describes the preparation, characterization, and applications of iron and osmium nanoparticles, respectively. Remarkable SERS activity has been observed on both iron and osmium nanoparticles-on-electrode settings. Both kinds of nanoparticles display the efficient electrocatalytic activity toward the redox of H2O2 and the oxidation of NO.
In chapter 5, SERS studies have been carried out on Cu2S nanowires array and single nanowire. When exposure to the laser irradiation, Cu2S nanowires may undergo disproportionating reaction and produce CuS and SERS-active Cu. SERS spectra of as-produced CuS, sub-layer Cu2S and pyridine adsorbates were obtained on single and multi nanowires at different potentials. SERS spectra of pyridine were also obtained from Ag and Au modified Cu2S nanowires.
Chapter 7 to 10 systematically presents high quality SEHRS and SERS spectra of various molecules including pyridine, pyrazine, benzene, 1,2-bis(4-pyridyl)acetylene, 1,2-bis(4-pyridyl)ethylene, 1,2-bis(4-pyridyl)ethane, 4-phenylpyridine, 4,4’-bipyridine, benzonitrile, and 4-cyanopyridine, obtained on efficient silver nanoparticles-on-smooth-silver-electrode settings at different potentials. The results demonstrate that the hyper-Raman spectra from noncentrosymmetric molecules contain the information of IR and Raman, while hyper-Raman spectra from centrosymmetric molecules provide the complementary information to IR and Raman. Ab Initio/DFT in conjunction with intensity calculations were employed to calculate normal modes of the molecules as well as their intensities in IR, Raman, hyper-Raman, SERS, and SEHRS to explore the adsorption effect and molecular orientation. The calculation results demonstrate that SEHRS spectrum is more sensitive to the molecular orientation than SERS.
Chapter 11 reports the high quality SEHRS and SERS spectra of thiol and disulfide based molecules at different potentials. The results demonstrated that thiol and disulfide molecules were chemisorbed on silver nanoparticles as thiolates via the interaction of sulphur to silver surface due to the cleavage of S-H and S-S bonds, respectively.
In chapter 12, SERS, SEHRS, and cyclic voltamnetry (CV) have been employed to study the electrochemical behaviors of 1-(4-pyridyl)pyridinium chloride hydrochloride on silver nanoparticles. The results demonstrated that organic film with polymeric structure was formed on silver nanoparticles as characterized by XPS and ToF-SIMS.
Chapter 13 presents the high quality SERHRS and SERRS spectra of dye molecules (rhodamine 6G, crystal violet, and basic fuchsine) adsorbed on silver NPSE setting. The results show that the high efficiencies of SERHRS have been obtained on silver nanoparticles, which is comparable to those obtained in silver sol but absolutely better than those obtained on roughened silver electrode. The results demonstrate the excellent generality of the as-developed silver NPSE setting in detecting SEHRS signals from both small and large molecules.
Chapter 14 presents the SEHRS and SERS spectra of tetra(4-pyridyl)porphyrin and ruthenium complexes for the first time, which demonstrate clearly the possibility to acquire SEHRS spectra from biological molecules and other molecules with the actual and potential applications with the help of efficient surface effect.