dc.contributor.advisor | Ertaş, Gülay | |
dc.contributor.author | Güvenç, Hacı Osman | |
dc.date.accessioned | 2016-01-08T18:05:36Z | |
dc.date.available | 2016-01-08T18:05:36Z | |
dc.date.issued | 2008 | |
dc.identifier.uri | http://hdl.handle.net/11693/14709 | |
dc.description | Ankara : The Department of Chemistry and the Institute of Engineering and Sciences of Bilkent University, 2008. | en_US |
dc.description | Thesis (Master's) -- Bilkent University, 2008. | en_US |
dc.description | Includes bibliographical references leaves 88-99. | en_US |
dc.description.abstract | A novel SERS substrate was prepared by coating Au or Ag nanoparticles onto
magnetic microspheres prepared by a modified suspension polymerization method.
The micron-sized magnetic microspheres were prepared in two steps: In the first step,
inorganic core which consisted of oleic acid coated magnetic magnetite nanoparticles
were prepared by co-precipitation method. The second step was the encapsulation of
oleic acid coated magnetite nanoparticles by a modified suspension polymerization
method. Magnetic microspheres were modified with amine functional groups in order
to immobilize Au or Ag nanoparticles onto magnetic microspheres via amine groups
of magnetic microspheres, however, a high background signal was obtained in Raman
measurements due to the amine groups. Alternatively, Au or Ag nanoparticles were
coated directly onto magnetic microspheres by hydroxylamine and sodium
borohydrate reduction methods for Au nanoparticle coating and sodium borohydrate
for Ag nanoparticle coating. For the first time, Au and Ag nanoparticle coated
magnetic microspheres were prepared and used as SERS substrate successfully. The magnetic microspheres were characterized by Scanning Electron Microscopy (SEM),
Fourier Transform Infrared Spectroscopy (FTIR), Energy dispersive X-Ray
spectroscopy (EDX) attached to SEM, Raman spectroscopy and X-Ray Diffraction
(XRD). The average size of magnetic microspheres is measured to be 22 µm from
their SEM images. EDX analysis demonstrated that magnetic microspheres were
coated with Au or Ag nanoparticles. Moreover, commercially available amine
functionalized magnetic microspheres were immobilized with Au nanoparticles and
its SERS activity was significantly than the Au nanoparticle coated magnetic
microspheres prepared in this study. Enhancement factors for Au and Ag nanoparticle
coated magnetic microspheres were calculated to be ca. 105
and 107
, respectively,
however, in case of Au nanoparticle immobilized Spherotech magnetic microspheres,
enhancement factor was only 2x102
using Rhodamine 6G as SERS probe. Interactions
of aspartic acid with Ag and Au nanoparticles were followed by Raman spectroscopy
at various pH values. pH dependent interactions of aspartic acid with Au and Ag
metals were followed depending on pH for the first time. Protonation or deprotonation
of amine or carboxyl groups on aspartic acid depending on pH of the solution affects
the interacting functional groups with metal nanoparticles and increase in the signal of
the corresponding group was measured. It is found that aspartic acid interacts through
amine and carboxyl groups with Ag surface at low pH values and via only carboxyl
groups at higher pH values. However, aspartic acid interacts with Au surface through
amine and carboxyl groups at all pH values under investigation. | en_US |
dc.description.statementofresponsibility | Güvenç, Hacı Osman | en_US |
dc.format.extent | xvi, 100 leaves, graphs | en_US |
dc.language.iso | English | en_US |
dc.rights | info:eu-repo/semantics/openAccess | en_US |
dc.subject.lcc | QC176.8.N35 G88 2008 | en_US |
dc.subject.lcsh | Nanoparticles. | en_US |
dc.subject.lcsh | Nanostructures. | en_US |
dc.subject.lcsh | Photochemistry. | en_US |
dc.subject.lcsh | Microspheres. | en_US |
dc.subject.lcsh | Raman effect. | en_US |
dc.subject.lcsh | Scattering (Physics) | en_US |
dc.title | Surface enhanced raman scattering from Au and Ag nanoparticle coated magnetic microspheres | en_US |
dc.type | Thesis | en_US |
dc.department | Department of Chemistry | en_US |
dc.publisher | Bilkent University | en_US |
dc.description.degree | M.S. | en_US |
dc.identifier.itemid | BILKUTUPB109227 | |