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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Summary of Findings

With classes starting in nearly two weeks, it’s time to wrap everything up by sharing my findings with you.  My time in the British Museum Archives really helped open my eyes about the institution, and revealed that many preconceptions are somewhat unfair. For example, the idea that the Museum goes out and steals artifacts from other nations and cultures is misleading. Yes, it is true the Museum occasionally funds digs, but most of their collection comes from donations or purchases from individuals or groups; in 1841 alone there were over 206 individual donors. Now it is possible these individuals obtained the objects in potentially questionable ways, but what is important is that the Museum was not directly involved in “looting”, something that appears throughout literature, and even in the public consciousness.

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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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After the fact review

After reaching the bottom of the wall in the second test unit, I filled both test units back in.  I washed the artifacts and with the assistance of Hayden Bassett and Maddy Gunter, was able to have them identified and recorded.  Artifacts relating to the fort’s occupation were a piece of north devonshire Stoneware, a piece of delft pottery mortared to the wall, and a few pieces of glass.  At the bottom of the wall three Amerindian pottery sherds were found.

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