AbstractThe main theme of this thesis is “ the exploration of molecular adsorption on plasmonic metal NPs via surface-enhanced Raman spectroscopy (SERS)”. The first work mainly focus on understanding and rationalizing the competitive adsorption of binary adsorbates on nanoparticles. 3D mathematic models which can accurately predict the final distribution of the binary thiols were successfully built by previous researchers in the group. The models were verified in this work and have been extended to non-thiol molecules. Besides, by combining theoretical and experimental methods together, a physical picture was established for the mathematical models, which gives a detailed description of the forces that influences competitive adsorption. The second work focus on studying the adsorption of poly hydrocarbons (PAHs). In this work, it was found that PAHs were selectively adsorbing on Au, but not Ag colloidal NPs, which breaks common perceptions that PAHs are non-adsorbing towards Au/Ag NPs. Mechanisms behind this finding was studied in this sections as well. The Third work demonstrates an important application (anticancer drug SERS monitoring) of the findings discussed in the second work, which demonstrates that unlike the common perception, the selection of the enhancing material composition for SERS measurement have a large effect on the final results. The final work introduces "potential well" effect of an advanced solid SERS substrates called surface-exposed nanoparticle sheets (SENS). Briefly, on SENS, NPs sit closely with each other and form plenty of SERS-active hot-spots. These hot-spots happen to be potential wells due to the overlap of charged capping agents on adjacent NPs. Based on such an effect, “super hot-spots” have been created through charge directed partial surface passivation which achieved to increase the signal of analytes by an order of magnitude.
Thesis embargoed until 31 July 2027.
|Date of Award||Jul 2022|
|Supervisor||Steven Bell (Supervisor) & Peter Nockemann (Supervisor)|
- Surface-enhanced raman spectroscopy
- self-assembled monolayer
- nobel metal nanoparticles
- surface selection rule