User:Julia C. MacDougall/Notebook/Quantum Dots/2014/03/28

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Objective

  1. Examine the differences in fluorescence color and appearance (particles suspended in solution or an aggregate) between the different solutions and buffer solutions (as prepared here [[1]] ).
  2. Synthesize another batch of the Mn-doped quantum dots using the same procedure as 1/31/14 [[2]]

Description

  1. The 22 test tubes were examined and the relationships between fluorescence color, solution v. aggregate appearance, composition, and buffer solution were explored. We attempted to find patterns between the results.
  2. Following the same procedure as the first solution as 1/31/14, it was necessary to add 200 microliters of NH4OH to each of the two test tubes. After the period of incubation at room temperature and the addition of sodium sulfide, the solutions were then incubated at 87C for 4 days, instead of 37C for 5 days.

Data

Table 1: Resulting Fluorescence Colors and Appearances

FluorescenceResults.png

Table 1 displays all of the results of the fluorescence colors and appearances, organized in a pattern of the buffers (1, 2, 3, etc.).

Notes

There were not too many significant trends in our data. The solutions resulting in a blue fluorescence ranged from 12-22.5% Manganese, and the solutions with an orange fluorescence ranged from 6.25-50% Manganese. This suggests that, because the higher Manganese concentrations typically result in the orange color, concentrations dictate the fluorescence. Because our sample size was so small, it is difficult to determine if such factors were actually responsible for the results. Among the buffers, two of those containing NaCl (solutions 1 and 6) were most effective in producing orange fluorescence. The pH 5 solutions produced the most orange solutions out of all (5/7). The trial would have to be expanded to determine whether these trends would continue with a larger number of solutions.

Additionally, all of Ben and Gabby's solutions fluoresced blue, 2/4 of Desi's were blue, and all of Julia and Nicole's solutions fluoresced orange. This raises the question of whether technique and overall amounts can contribute to the fluorescence; it is believed that Gabby and Ben's overall solutions might have been half the volume of Desi, Julia, Nicole, and Dr. Harting's, but the concentration values are all valid.

The questions we have include whether adding more Manganese would always lead to orange fluorescence, whether pH plays a large role in fluorescence, and what would happen in solutions with similar Manganese and Zinc values because only one solutions was close to 50% Manganese. These questions could possibly be answered by expanding the study.