Flourescence and self-absorption cause shift in wavelength

In summary, fluorescence occurs when there is a difference between the absorption and emission wavelengths, but at higher concentrations, self-quenching can occur which reduces the intensity of the emission and can also cause a shift in the peak fluorescence wavelength. This is due to the formation of complexes between fluorophores, changing their electronic properties and altering the energy levels of the molecules.
  • #1
fog37
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Hello Forum,

I understand how fluorescence works: there is an absorption spectrum and an emission spectrum. The two spectra are shifted relative to each other in the sense that the absorption peak wavelength is different from the emission peak wavelength (Stokes shift).
That said, fluorescent dyes may also fluoresce differently at high concentrations (self-quenching).

Self-quenching reduce the intensity of the fluorescent emission but can also leads to a shift of the peak fluorescence wavelength. Why? Why would the higher concentration and self-absorption between the clorophores cause a shift in the emission wavelength? A molecule absorbs the fluorescent light emitted by the other...Thanks,
Fog37
 
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  • #2
Self-quenching, in general, is not due to one fluorophore absorbing the emitted light of a neighboring fluorophore. In many cases, self-quencing occurs due to excimer or exiplex formation – fluorophors physically interacting to form complexes that can change their electronic properties (for example, providing new non-radiative pathways for relaxation, explaining the lowered quantum yield, and altering the energy levels of the molecules, explaining the shifted emission spectrum).
 

What is fluorescence?

Fluorescence is a phenomenon where a substance absorbs light at a certain wavelength and then emits light at a longer wavelength. This process is often used in scientific research and in everyday products, such as fluorescent light bulbs.

How does fluorescence cause a shift in wavelength?

When a substance absorbs light, the energy of the absorbed light is used to excite the electrons in the substance to a higher energy state. As the electrons return to their ground state, they emit light at a longer wavelength, causing a shift in wavelength.

What is self-absorption in terms of fluorescence?

Self-absorption is when the emitted light from a fluorescent substance is reabsorbed by the substance itself. This can cause a decrease in the intensity of the emitted light and can also cause a shift in the wavelength of the emitted light.

How does self-absorption affect the accuracy of fluorescence measurements?

Self-absorption can affect the accuracy of fluorescence measurements by causing a decrease in the intensity of the emitted light, which can lead to a lower signal-to-noise ratio and make it more difficult to detect the fluorescence. It can also cause a shift in the wavelength, which can affect the interpretation of the data.

What are some ways to minimize the effects of self-absorption in fluorescence measurements?

Some ways to minimize the effects of self-absorption include using a lower concentration of the fluorescent substance, using a different excitation wavelength, or using a different solvent that may reduce self-absorption. Additionally, using a correction factor or performing a self-absorption correction calculation can also help improve the accuracy of fluorescence measurements.

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