What is the importance of calculating the stokes shift in PL spectra?
The importance of the Stokes shift is not only a practical one, but it can also give you insight on what happens to the fluorescing system in the excited state. Small stokes shift means small geometrical relaxation and small solvation effects once the chromophore is excited. Large stokes shift means large geometrical relaxation and/or solvation effects.
The difference between positions of the band maxima of absorption
and fluorescence of the same electronic transition is known as Stokes
shift. Stokes shift is important for practical applications of fluorescence
because it allows separating strong excitation light from weak emitted
fluorescence using appropriate optics.
Dear Sheik Mohammed! You must to give definition of PL.
May be it is interesting for you publication from Russia: V. E. Ogluzdin. UFN {bf \ 176} 415 (2006).
Dear Sheik Mohammed! You must to give definition of PL.
May be it is interesting for You publication: V. E. Ogluzdin. UFN {bf \ 176} 415 (2006).
The importance of the Stokes shift is not only a practical one, but it can also give you insight on what happens to the fluorescing system in the excited state. Small stokes shift means small geometrical relaxation and small solvation effects once the chromophore is excited. Large stokes shift means large geometrical relaxation and/or solvation effects.
I think it would be more appropriate to measure the shift between the peak of excitation spectrum of that particular emission. Absorption spectrum may refer to the excitation of more than one emission peak.
You must to give definition of PL. What is PL??? May be it is interesting for You publication from Russia (in English): V. E. Ogluzdin. UFN {bf \ 176} 415 (2006).
To measure the Stokes shift you may first get the photoluminescence spectrum. Then you calculate the energy E1 corresponding to the maximum of the spectrum. Next you fix the registration wavelength L1 at the spectrum maximum and start to change the excitation wavelength in a certain region (measuring excitation spectrum) looking for the excitation wavelength L2 providing maximum luminescence at the registration wavelength you have fixed. Next you calculate the energy E2 corresponding to L2 wavelength. The difference E2 – E1 will show you the Stokes shift.
Dr. Messina, Dr.Mathur, Dr Ogluzdin and Dr.Zaytsev for your valuable answers.
Could anyone pl specify a good review article in this area.
To Dr Ogluzdin, since i am in remote area of India, i couldn't access the paper you have mentioned. Could u pl send me the paper. Thank you sir
You may take a look at this material:
http://www.wiley-vch.de/books/sample/3527316698_c01.pdf
Thanks a lot Dr. Zaytsev for sending me a material. I have gone through it. Now, I could able to clearly understand the concept of stokes shift.
Dear Sheik mohammed abdul kader!
To understand nature and quantity of Stokes or antiStokes shifts of the photoluminecsence (PL), it is necessery to know lines of absorptions of media, and to produce calculations in compliance with law conservation of energy.
V. Ogluzdin
To understand nature and quantity of Stokes or antiStokes shifts of the photoluminecsence (PL), it is necessery to know lines of absorptions of media, and to produce calculations in compliance with law conservation of energy.
About photoluminecsence -see attach. V.Ogluzdin.
Dear Dr. Sheik Mohammed Abdul Kader,
Thank you for your question on the particular topic regarding the Stokes Shift.
I have only some comment/remark. The fundamentals of the Stokes Shift are explained on the basis of Jablonski scheme and Frank-Condon Energy diagram (they are available elsewhere). The basic point of this explanation concerns the concept of the average distance of molecular separation. This distance is smaller for the system in its basic initial state as compared to the excited state. Thus, hypothetically, the Stokes Shift contains the information about the increase of the effective molecular radius in the excited state. However, I did not run across in literature any analytical calculations of how to estimate it. I would also appreciate anybody’s comments or/and references on this point.
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