Link to the University of Pittsburgh Homepage
Link to the University Library System Homepage Link to the Contact Us Form

Spectroscopic Investigations of Nanoscale Aggregates and Their Electron Transfer Properties in Solution

Wu, Mingyan (2011) Spectroscopic Investigations of Nanoscale Aggregates and Their Electron Transfer Properties in Solution. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

Primary Text

Download (5MB) | Preview


In part I, the changes in the absorption and fluorescence properties of poly-(p-phenylene-ethynylene) (PPE)-based conjugated polyelectrolytes were investigated as a function of the solution conditions such as concentration, temperature, solvent, surfactant, and the ionic strength. The equilibrium between unaggregated and aggregated forms of the polymer was described and quantified. The fluorescence quenching of polymers by positively charged and neutral macromolecules were also investigated and showed that the quenching depends on electrostatic, hydrophobic, and energy transfer interactions with the quencher. A detailed study using fluorescence correlation spectroscopy was performed and allowed us to probe the templating of a surfactant OTAB on the polyelectrolytes well below its critical micelle concentration. Furthermore, it was found that the optical and aggregation properties of these conjugated polyeletrolytes can be manipulated by changing the charge density along the polymer backbone. In part II, assemblies of CdSe and CdTe NPs were controlled by the electrostatic attraction of the charged functionalities placed on the NP surface coating. Electron transfer (ET) in assemblies of these NPs was studied in aqueous solution by fluorescence quenching. Three factors were found to determine how the ET depends on the nature of the NP assemblies by both steady-state and time-resolved fluorescence measurements: the interparticle distance, the energetic alignment of the NP bands (hence the size of the NPs), and the direction of the electric field between the NPs, created by their surface charges. In addition, the assemblies of CdSe NPs on a dithiol coated Au electrode were created and their electronic energetics were quantified. The energy level alignment of the filled and unfilled electronic states of CdSe NPs with respect to the Au Fermi level was investigated by both cyclic voltammetry and photoemission spectroscopy separately. These two measurements showed that the CdSe filled states become ‘pinned' to the Fermi level of the Au electrode. Furthermore, the preliminary electrochemical studies at the interface were carried out in order to investigate the organization and reactivity of nanoparticles/dyads at ITIES.


Social Networking:
Share |


Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairWaldeck, David H. dave@pitt.eduDAVE
Committee MemberLee, Jung-Kunjul37@pitt.eduJUL37
Committee MemberSaxena, Sunilsksaxena@pitt.eduSKSAXENA
Committee MemberMeyer, Taratmeyer@pitt.eduTMEYER
Date: 30 September 2011
Date Type: Completion
Defense Date: 3 June 2011
Approval Date: 30 September 2011
Submission Date: 22 July 2011
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: aggregates; conjugated polymer; electron transfer; nanoparticle; polyelectrolyte; solar cell.; spectroscopy
Other ID:, etd-07222011-101340
Date Deposited: 10 Nov 2011 19:53
Last Modified: 15 Nov 2016 13:46


Monthly Views for the past 3 years

Plum Analytics

Actions (login required)

View Item View Item