Title:
Fluorescent noble metal nanoclusters

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dc.contributor.advisor Dickson, Robert M.
dc.contributor.author Zheng, Jie en_US
dc.contributor.committeeMember El-Sayed, Mostafa A.
dc.contributor.committeeMember Lyon, Andrew L.
dc.contributor.committeeMember Wang, Zhong Lin
dc.contributor.committeeMember Whetten, Robert L.
dc.contributor.department Chemistry and Biochemistry en_US
dc.date.accessioned 2006-06-09T18:27:41Z
dc.date.available 2006-06-09T18:27:41Z
dc.date.issued 2005-04-19 en_US
dc.description.abstract Water-soluble fluorescent metallic clusters at sizes comparable to the Fermi wavelength of an electron (~0.5 nm for gold and silver) were created and their photophysical properties were investigated at the bulk and single molecule levels. We employed biocompatible dendrimer and peptide to prepare a series of strong fluorescent gold and silver clusters with chemical or photo reduction methods. Facilitated by the well-defined dendrimer size, electrospray ionization mass spectrometry indicates that the fluorescent silver nanocluster size ranges from 2 to 8 Ag atoms. The correlation of emission energy with the number of atoms, N, in each gold nanocluster is quantitatively fit for the smallest nanoclusters with no adjustable parameters by the simple scaling relation of EFermi/N1/3, in which EFermi is the Fermi energy of bulk gold. The transition energy scaling inversely with cluster radius indicates that electronic structure can be well described with the spherical jellium model and further demonstrates that these nanomaterials are multi-electron artificial atoms. Fluorescence from these small metal clusters can be considered protoplasmonic, molecular transitions of the free conduction electrons before the onset of collective dipole oscillations occurring when a continuous density of states is reached. In addition, very strong single molecular Stokes and Antistokes Raman enhancement by fluorescent silver clusters was observed. Pushing to larger sizes, we also created ~ 2nm diameter glutathione encapsulated luminescent gold nanoparticles. Distinct from similarly sized but nonluminescent gold nanoparticles, these 2 nm gold nanoparticles show bright, long lifetime emission but no plasmon absorption. The emission might arise from charge transfer between gold atoms and the thiol ligand. Providing the missing link between atomic and nanoparticle behavior in noble metals, these highly fluorescent, water-soluble gold and silver nanoclusters offer complementary transition energy size scalings at smaller dimensions than do semiconductor quantum dots. The unique discrete excitation and emission and strong Stokes and antistokes Raman enhancement coupled with facile creation in aqueous solution open new opportunities for noble metal nanoclusters as biological labels, energy transfer pairs, and other light emitters in nanoscale electronics. en_US
dc.description.degree Ph.D. en_US
dc.format.extent 2082443 bytes
dc.format.mimetype application/pdf
dc.identifier.uri http://hdl.handle.net/1853/10574
dc.language.iso en_US
dc.publisher Georgia Institute of Technology en_US
dc.subject Nanoparticles en_US
dc.subject Biocompatible
dc.subject Nanoclusters
dc.subject Single molecule
dc.subject Noble metal
dc.subject Fluorescent
dc.title Fluorescent noble metal nanoclusters en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.advisor Dickson, Robert M.
local.contributor.corporatename School of Chemistry and Biochemistry
local.contributor.corporatename College of Sciences
relation.isAdvisorOfPublication 328b7195-8f0f-4be1-a8e9-90ba4c20fb59
relation.isOrgUnitOfPublication f1725b93-3ab8-4c47-a4c3-3596c03d6f1e
relation.isOrgUnitOfPublication 85042be6-2d68-4e07-b384-e1f908fae48a
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