Jul
13

Questions, questions, questions…

With more than half of the summer gone by, I still have more questions than answers regarding my molecule, eosin y (EY), and its properties. When I last left off, I was trying to figure out how the pH dependence impacts the structure and how I could isolate just one form of the dye. It turns out that in ethanol I only have one form of the dye, so that’s one problem solved.

However, more investigation into the blinking dynamics have led to many, many more questions. Typically we spin coat the dyes onto glass and then put them in nitrogen—this helps to stabilize them and prevents them from reacting with oxygen. Earlier in the summer, I had forgotten to turn on the nitrogen, and the blinking we saw in air was wildly different from what we saw in nitrogen. Since then, I have been trying to quantify this and understand why its so different and why it appears that EY is so active in air. The molecules also fluoresce for long periods—I’ve measured it up to 1000 seconds under laser excitation. In nitrogen, it dies within 200 seconds. So what is it about air that makes EY live so long?

As I dig further into what makes EY such an interesting molecule, we have been inspired by research from other groups to try some new techniques. Specifically, I am investigating the bin time dependency of EY. Bin time is essentially how frequently the photon detector sends fluorescent information to the computer. At a 10 ms bin time, the detector collects the fluorescent intensity every 10 ms. Other groups have shown that by lowering the bin time, its possible to measure blinking dynamics that occur on a faster timescale. For example, if electron movement happens on the scale of 1 ms, we won’t be able to see these short time events if we are only collecting data every 10 ms. I have been experimenting with lowering the bin time and analyzing this data to determine if there is anything worth pursuing. I have spent much of the past week running various data sets through MATLAB and comparing results in order to decide how to best handle the information and if its possible for us to dig deeper into the question of bin time dependence.

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