100 molecules to go


I have just completed my first week of summer research and have set a few short term goals for the following week. I am currently focusing on two things: data collection and literature research. I am continuing my work from the school year of collecting blinking traces of Rhodamine B (RB) dye on TiO2. To quickly recap, the RB dye is diluted with water and TiO2 to 1e-9M. This solution is then spin-coated onto a blank slide and analyzed under a confocal microscope. A laser is then used to hit the slide, resulting in fluorescent molecules, a photon detector and scanning acquisition program then produces an image, in which molecules show up as bright spots. Once the molecules are located, each one is hit with the laser and blinking are traces are collected as the molecule switches from on (fluorescent) states to dark states(Fig.1).  Once in a permanent dark state, the molecule is photo-bleached. Data collected on a photo-bleached molecule provides no useful information, so I am experimenting with different factors to increase the molecules stability for longer data collection time. Currently, molecules are put in a Nitrogen atmosphere for increased stability. The power of the laser also effects how long the molecule may fluoresce until being photo-bleached, and currently the best power has been a wave plate length of 20nm. Half of the times blinking traces are collected, however the other times the molecules are already photo-bleached. There are some cases where the molecules begin to fluoresce after certain periods of times, making it difficult to know if a molecule is truly photo bleached.  As more data is collected this week, I hope to better understand patterns and time duration of the blinking traces. The goal is to collect useable data from 100 molecules! Currently I have 28, I guess I have a ways to go.

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