Next Step: Titanium Dioxide

During my last week of research, I started a new phase of my project. After completing the study of the electron transfer dynamics of the dye Rhodamine 560 on glass, I moved on to studying the behavior of this dye on titanium dioxide. While we can learn a lot from the studies of R560 on glass especially when we compare it to other rhodamine dyes on glass, that entire phase of experimentation was just a control for comparison with the results on titanium dioxide. In actual dye-sensitized solar cells, the application of this research, titanium dioxide or some other semiconductor is necessary for the generation of electricity.

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Bare Nanoparticle Quenching and Future Work

Towards the end of this summer I was able to reproduce fluorescence quenching on bare nanoparticles. Upon photoexcitation by the laser (or sunlight), there is a locally enhanced electromagnetic field produced around the nanoparticle. As mentioned in previous posts, a fluorophore oriented closer to the surface of a plasmonic particle will experience a greater EM field. However, fluorophores located too close or touching the surface of a particle will undergo quenching of fluorescence because of the significantly stronger EM field. To save some time, I will not go into a lengthy discussion on the exact science behind quenching, mainly because I don’t understand most of it. In this context all we are concerned with is the fact that fluorophores located on the surface of bare nanoparticles are showing a decreased fluorescence enhancement. As opposed to positive ratios, the quenched particles show up as dark spots on a bright background, meaning these particles are emitting less photons than the background dye. A typical correlated fluorescence scan and LSPR image of bare NPs can be seen below. After analyzing 25 particles, the average enhancement was 0.84 ± 0.07. 25 particles isn’t necessarily a substantial amount, but the quenching measurements thus far prove the background theory.

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Analyzing Fluorescence Enhancement for Medium-Thick SCNPs

Sorry for the long hiatus, the last few weeks of research were quite hectic. Simultaneously trying to wrap-up experimentation for the summer, compiling tons of data, and preparing for the coming semester is a daunting task.

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Correlating Single Dye Molecule Fluorescence with Nanoparticle LSPR

It’s always tough when research doesn’t go the way you initially planned. Spending weeks on a certain project only to discover that the data doesn’t fully prove the hypothesis is beyond frustrating. Alas, that’s science.

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Data, Thou Art A Fickle Mistress

Since my last blog, I have run A LOT of fluorescence scans on silica coated silver nanoparticles. It’s safe to say that my daily emotions are directly linked to the outcomes and efficiency of these scans. One day I could successfully analyze fluorescence enhancement ratios for up to 20 nanoparticles and another day I could get as little as 2. For instance, I severely misaligned the laser on accident one day and it took us over an hour to fix the problem! Sometimes I feel like even the laser hates Mondays…But, alas, I am making progress on compiling data.

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