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1. The figure below shows overlaid absorption and fluorescence emission spectra of quinine solution. Answer the following questions. [35 pt] 100- Stokes shift Emission 80- Absorption 60- 40- Sots, S. So 20 So-S2 300 350 400 450 500 550 600 Wavelength (nm) A. If quinine molecules are excited at 300 nm wavelength, predict at which wavelength the fluorescence intensity shows the highest intensity. Justify your answer using the Jablonsky energy diagram. To receive full credit, label the energy states and all possible pathways of the excited quinine molecule and calculate differences in each energy state in nm and cm!. [10 pt] B. The structure of quinine is shown below. Predict the part of the molecule that is most likely to behave as the fluorescence center. Draw the structure on your answer sheet and circle the part. [5 pt]
OH c. You want to analyze the amount of quinine in tonic water using a spectrofluorometer and construct a linear calibration curve using the calibration standard solutions of quinine. You want to use a 350 nm wavelength as an excitation light source to measure the fluorescence emission. What would be the maximum concentration of the quinine solution (in the Molarity unit) to expect a linear trend in the calibration curve? Justify your answer to receive full credit. [10 pt] D. The excitation light source and the PMT detector in a spectrofluorometer are placed at a 90° configuration. Explain why. [5 pt] E. The excitation spectrum obtained with a spectrofluorometer resembles the absorption spectrum obtained with a UV-Vis absorption spectrophotometer. Explain why. [5 pt1 2. Consider schematin die