[Optics] Questions on the Stokes shift

In summary, Stokes shift refers to the difference in wavelength between the excitation and emission spectra of the same electronic transition. A larger Stokes shift means there is a greater energy loss, which is not favorable for energy efficiency. However, it also results in a higher signal-to-noise ratio (SNR), making it easier to identify fluorescence emission from observed particles. This is because a larger Stokes shift leads to a greater difference in wavelength between the excitation and emission light.
  • #1
rinalai
19
5
Homework Statement
Is it better to have a large or small Stokes shift, from a practical point of view?
Relevant Equations
NA
Here is my answer to this question:

Stokes shift is the difference in wavelength between positions of the band maxima of the excitation and emission spectra of the same electronic transition.
When Stokes shift is large, it means there is more energy loss, which is not favorable regarding energy efficiency. Thus, it is usually better to have a small Stokes shift.
On the other hand, with a larger Stokes shift, meaning that there is a greater wavelength difference between the excitation and emission light, resulting in a higher signal-to-noise ratio(SNR), which makes it easier to identify the fluorescence emission from the particles we are observing.

Are these statements correct?
Any comments and suggestions will be appreciated.
 
Physics news on Phys.org
  • #2
I have no idea what it means to be "practical". Practical in what sense?

rinalai said:
On the other hand, with a larger Stokes shift, meaning that there is a greater wavelength difference between the excitation and emission light, resulting in a higher signal-to-noise ratio(SNR), which makes it easier to identify the fluorescence emission from the particles we are observing.
Why do you think that larger Stokes shift lead to higher SNR?
 

FAQ: [Optics] Questions on the Stokes shift

1. What is the Stokes shift?

The Stokes shift is the difference in energy between the absorption and emission of a photon by a molecule. It is caused by the relaxation of the molecule from an excited state to a lower energy state.

2. How is the Stokes shift measured?

The Stokes shift can be measured by using a spectrophotometer, which measures the absorption and emission spectra of a molecule. The difference in the peak wavelengths of the spectra corresponds to the Stokes shift.

3. What factors affect the magnitude of the Stokes shift?

The magnitude of the Stokes shift is affected by the molecular structure, solvent polarity, and temperature. Molecules with larger structures and higher polarizability tend to have larger Stokes shifts, while more polar solvents and higher temperatures can decrease the magnitude of the shift.

4. How is the Stokes shift used in fluorescence spectroscopy?

In fluorescence spectroscopy, the Stokes shift is used to determine the energy difference between the excitation and emission wavelengths of a molecule. This can provide information about the electronic structure and environment of the molecule.

5. What are some applications of the Stokes shift?

The Stokes shift has various applications in fields such as biochemistry, material science, and environmental monitoring. It can be used to study protein structure and dynamics, identify pollutants in water, and characterize the properties of organic and inorganic materials.

Similar threads

Back
Top