Pre-Assignment

1. What are the advantages of using fluorescein molecule for pH-dependent fluorescence studies?
2. What kind of electronic transition is responsible for fluorescence in fluorescein molecule?
3. Which proton is lost last from the fluorescein molecule when fluorescein reacts with NaOH?
4. Methanolic solution of fluorescein is acidic, pH= 4. How can you explain this?

Post-Assignment

1. Out of two carboxylic acid forms, which form of fluorescein molecule fluoresces most intensely?
2. Which molecular form of fluorescein molecule requires more energy for electronic transition?
3. Why did the shoulder peaks appear in the excitation and emission spectra when NaOH was not added?
4. How do the Stokes shifts vary depending on the pH of the solution?