I am studying the interaction between carbon dots and fluorescent organic dyes like Rhodamine 6G, which have an overlap between the emission of the CDs and absorption of the dyes.
In spectroscopic analysis, as I increase the concentration of the dyes in the CDs solution, the emission peak quenches, while the fluorescence lifetime increases as the concentration of the dye increases. Additionally, the emission intensities of the dyes increase. In a typical FRET (Förster Resonance Energy Transfer) process, the emission of the carbon dots is expected to decrease, and the emission of the dye is expected to increase. This is happening with my samples, but the fluorescence lifetime of the CDs is expected to decrease. However, in my CDs sample, the lifetime increases as I increase the amount of the quenching dyes.
Can you please share suggestions to understand this anomalous observation?.
Is the fluorescence decay of CD monoexponential? If not, may be the analysis of the decay curve's content (like lifetimes of components and their relative contributions) will give some information to think about? I am not quite familiar with CD fluorescence, but is it possible that they contain e.g. two types of emission centers, with longer and shorter decay times, and R6G comes close predominantly to those with shorter times?
Thanks for your reply. CDs exhibit a monoexponential FL decay.
If you want, I can share some figures with you to make it clear.
If FRET is occurring in your system, the donor's lifetime should decrease. The observed decrease in photoluminescence (PL) indicates that reabsorption might be taking place. To address this, you need to perform secondary inner filter correction.
Debabrata Chakraborty - but in the case of reabsorption, decay time would not change?
Muhammad Sami - you may send me figures if you wish, may be it becomes more clear (but I am not sure...)
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