Week #6 Update

This week’s research mainly consisted of continuing to take more data of EY on TiO2 under both oxic (air) and anoxic (N2) environments. We have been continually taking blinking trace data of these single molecules. By continually building a larger data set, we can then move towards running the data set through clauset analysis. This allows us to see how well distributions of ON segments and OFF segments of our blinking data fit to certain distributions. These distributions will give us insight into the underlying kinetics of EY. We have continued to parse out the contaminated data and also considering whether certain molecules on the border of ‘good’ and ‘bad’ should be included or not. Additionally, after compiling multiple workups of our scans and corresponding blinking traces, we have a more concrete idea of how EY on TiO2 should qualitatively look like, in air and N2 compared to EY on glass.

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Week #5 Update

During the previous week, I had issues with contamination of my sintered blank glass and sintered TiO2 batches I make using the muffler furnace. After cleaning the oven by heating it at 1000C. However, after making this week’s batch I noticed I still had contaminants. The new protocol for properly ridding of these contaminants is now to heat the oven at 1000C for a few hours beforehand for every batch made. With this resolved, I have continued taking scans of EY on TiO2 at 5×10^-10M concentrations to continue building a data set. Within this data set, molecules are determined as either good or bad via a threshold. This threshold utilizes a CPD3dark Matlab code that allows us to compile blinking traces taken of just blank glass with TiO2. This determines a threshold that accounts for just the laser itself, rather than any photophysical events. I plan on refining this threshold in order to essentially increase our ‘good’ molecules and further increase the usable data set. This will be done by taking more of these blinking traces of blank sintered TiO2 Further distinguishing of contaminated data will done to ensure our data set contains truly ‘good’ molecules and nothing else, parsing out our contaminated data.

Week #4 Update

Continuing research during this week, I noticed contamination of my sintered blank glass slides. Scans of these slides showed high counts and multiple spots showed contamination. These slides should in theory show very few counts, as they are simply just blank glass. To try and deduct the source of this contamination I scanned blank glass slides that were not sintered, thus never placed in the muffler furnace. To my surprise, I found that the slides showed little contamination, being what we expected our sintered slides to be. I decided to remake a new batch of sintered blank glass and TiO2 slides. After taking scans of these, contamination was still found. The next logical assumption would point to the muffler furnace itself. The next day, to cleanse the furnace, we held the muffler at 1000 degrees Celsius, airing it out every hour to try and dismiss any possible contaminants from within the oven itself. Sure enough, new batches of sintered blank glass and TiO2 made after this cleansing were seen to show very little contamination, and has seemed to resolve the problem.

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Week #3 Update

The third week of my research has mainly consisted of continuing scans of EY on TiO2 at 5×10^-10M, single molecule concentrations. I have been taking scans of EY on TiO2 under different laser power settings. This was done after retaking power measurements to create an updated power chart based on waveplate and ND filter settings. The goal of experimenting with different laser powers is to achieve single molecule densities similar to EY on Glass substrate. Through this, data collection of blinking traces becomes more efficient and our scans are also more easily comparable between the two Glass and TiO2 substrates. Experimenting with these different powers, I determined the most optimal power to be 1.45uW which achieved the molecular densities desired, while not being too much power to result in photobleaching nor too underwhelming, such that seeing single molecules on scans becomes difficult.

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Week #2: TiO2 Control Experiments

This second week of research, I have been continuing with control experiments. I have been working to confirm whether our slides are truly coated with a TiO2 film under scans of our samples. We have been looking at Eosin-Y dye on TiO2 films, but still need to ensure that the scans we are taking are indicative of EY on TiO2 rather than just plain glass. To accomplish this, I prepared a new aliquot of TiO2 from the original bottle. I then used this aliquot to prepare a batch of TiO2 and blank glass for sintering in the oven. The TiO2 is spincoated onto base bathed glass slides. We then sinter the batch of slides in a muffle furnace to rid the slides of impurities. With this, we take the slides and then spincoat our desired dye, in our case, EY onto the slides. This was done with EY at 1×10^-6M concentration, a high enough concentration for us to notice a significant difference between EY on glass and EY on TiO2. With this, we expect to have a consistent method to confirm whether our batches have TiO2 on them. As far as differences in the scans of EY on glass vs. TiO2, we expect to see less fluorescence and decreased photon counts with the TiO2, as it is a metal substrate that offers an alternative pathway, for the electrons to transfer onto the TiO2 substrate.

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