Spectrofluorimetry/Fluorimetry/Fluorescence Spectroscopy|Principle, Instrumentation, Applications

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This video explains about the principle of fluorescence spectroscopy or spectrofluorimetry. It discusses the process of fluorescence with the Jablonski's diagram. It distinguishes the difference between excitation and emission spectrum. The instrumentation of spectrofluorimetry is discussed. The advantages, disadvantages and applications of spectrofluorimetry are also enumerated.
You will be able to
discuss the principles of spectrofluorimetry
State Stoke’s law or Stoke’s shift
distinguish between the excitation and emission fluorescence spectrum
explain the instrumentation in detail and working of spectrofluorimetry
list out the advantages, disadvantages and applications of spectrofluorimetry.
Principle of Spectrofluorimetry/ Principle of Fluorescence spectroscopy
Spectrofluorimetry or fluorescence spectroscopy is a technique in which UV/Visible light is absorbed by electrons in singlet ground state to move to singlet excited state and returns back to the singlet ground state by emitting radiation (fluorescence) with lower energy (longer wavelength) or same energy to give rise to fluorescence spectroscopy.
Excitation fluorescence spectrum
Emission fluorescence spectrum
Stoke’s shift or Stoke’s law
The fluorescence occurs at a longer wavelength than the excitation wavelength (Difference between the wavelength of emission maxima and absorption maxima)
Resonance fluorescence
The fluorescence wavelength is equal to the excitation wavelength (The process of re-emitting the absorbed energy in the form of light).
Excitation spectrum
plot of intensity of fluorescence emission as a function of excitation wavelength.
Lowest vibrational level of S0 to any vibrational level of S1, S2 etc.
So a band is obtained.
Emission/Fluorescence spectrum
plot of intensity of fluorescence emission against the emission wavelength.
Lowest vibrational level of S1 to any vibrational level of S0.
So a band is obtained.
Instrumentation & working of Spectrofluorimetry/ Instrumentation & working of Fluorescence spectroscopy
Source – Supplies light in the l = 200-800nm - Xenon lamp.
Excitation monochromator – Allows only the excitation wavelength one at a time and absorbs all the other wavelengths and this happens for the complete chosen range of wavelength. eg. diffraction grating.
Sample cell (cuvette) – Sample is placed in it and the cell is polished on all the four sides, as the fluorescence emission is measured at 90o to the incident light. eg. quartz.
Emission/Fluorescence monochromator - Allows only the emission wavelength one at a time and absorbs all the other wavelengths and this happens for the complete chosen range of wavelength. eg. diffraction grating.
Detector – It detects the intensity of the fluorescence light for each wavelength and generates current proportional to it. eg. photomultiplier tube.
Recorder – It records
Excitation fluorescence spectrum – plot of intensity of fluorescence as a function of excitation wavelength.
Emission fluorescence spectrum - plot of intensity of fluorescence against the emission wavelength.
Advantages of Spectrofluorimetry/Advantages of Fluorescence spectroscopy
High sensitivity (ng/ml to mg/ml).
High selectivity (fluorescent substances show specific excitation and emission lmax value).
Disadvantages of Spectrofluorimetry/Disadvantages of Fluorescence spectroscopy
All compounds do not fluoresce.
It is not suitable for identification of compounds.
Contaminants can quench fluorescence and mislead the results.
It is susceptible to pH, solvent polarity, temperature etc.
Applications of Spectrofluorimetry/Applicationsof Fluorescence spectroscopy
Fluorescent probes to detect biological compounds.
Detection of the environmental pollutants.
In geology many minerals and gems can be identified.
Steroids, proteins, plant pigments, drugs can be identified even at low concentrations.
Fluorescent compounds in TLC plates.
Fluorescent detectors are used in HPLC.
Determination of vitamins in food samples, natural products, pharmaceuticals, clinical samples.
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I had a hard time trying to find explanations that remains clear and simple while covering all the areas of the topic, and you did it really well. Thank you!

hAILeyson
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This is my introduction to your channel and i must say, great work! My background is in Zoology & i found this helpful. Thanks!

RohitPant
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Thank you so muth you literally explained everything!! : difference between emission and excitation, why measure on 90°.etc..
Those are all the things I couldnt find on google or in my spectrofotometry book!

moun
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Very good and straight forward class. Congratulations madam.

palethmuhammedrazi
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Discovered this channel didn't expected such good content.... subscribed ✌️

Modest_Muse
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Brilliant explaination..i really learnt Spectrofluorimetry

nchimunyamuloongo
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It was really very helpful i was struggling to understand it and u made it very simple

muskanborana
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Mam it's was amazing 🤩 and really helpfull... thank you so much 💞

gul_e_aziz
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Thanks mam for this lecture I found it so helpful 🙂

pratimapatel
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Thank you so much ✨🩷brilliant explanation 👌all main questions answers in one video 🥹

shrustikhewale
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Great explanation ma'am! Thank you!

architkadu
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how could we know whether the compound can be measured through fluorescence. and Can I use DPPH free radical assay for antioxidant with the spectrofluorimetry

KeerthiBandaru-hc
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Mam, can you please tell me some examples of the substance that are not naturally fluorescent.. But we provide them fluorescence

pallavidandge
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Please discuss thermal analysis (all methods) and XRD please

smk
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very good presentation Mam. By the way do you have the ppt of this? If you have please share it so that it will be useful for every one

akhilthota
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Hi ma'am,
Please discuss acid-base titration curve and also discuss indicator

Ma'am mera exam November se start h so please thoda jaldi cover kijiye ga ye topic 🙏🙏🙏🙏🙏

Bhagat
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I did not find the link which you have mentioned in the video.

sachinrajpandey
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Is fluorescence spectroscopy or fluorescence spectrophotometry same??

rachna
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Can u put vedios based on pgt sylabus madam

ktschemistry
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Fluorimetry and spectro fluorimetry both same or not

harshinisweety