UV Vis Spectroscopy Band gap Calculator

UV Vis Spectroscopy Band gap Calculator


Calculation Tutorial:

STEP1: Open the absorption graph of the material, which is obtained from the UV Vis spectroscopy. W a v e l e n g t h I n t e n s i t y 200 220 240 260 280 300 0.0 0.2 0.4 0.6 0.8 1.0 STEP2: Now zoom on the area for which you want to calculate the band gap and note down the wavelength (λ) at which absorption peak is shown. W a v e l e n g t h I n t e n s i t y 200 220 240 260 280 300 0.0 0.2 0.4 0.6 0.8 1.0 220 STEP3: Now enter the measured wavelength value (eg. 31.8) into the " Wavelength of Absorption peak (in nanometer)" column of the calculator. You should get the calculated results of the band gap in the "Calculated Result" field.

Theory Behind Calculations: UV Vis Spectroscopy absorption peak means the Electrons are absorbing the Energy at some specific wavelength. Electrons are absorbing Energy means the Electrons are going to excited state from its ground state. Electrons are going to excited state from its ground state means the material is having band gap, thus which can be determine by absorption wavelength.

Energy Equation of Quantum Mechanics:

Energy (E) = Planks Constant (h) * Speed of Light (C) / Wavelength (λ)

Where, Energy (E) = Band gap, Planks constant (h) = 6.626×10^-34 Joules sec, Velocity of Light (C) = 2.99×10^8 meter/sec and Wavelength (λ) = Absorption peak value. Also 1eV = 1.6×10^-19 Joules (Conversion factor)

By this formula band gap can be calculated easily, from UV Vis spectroscopy absorption peak.

Post a Comment

  1. This is the useful and usual formula used to calculate the energy gap from the absorption spectra in the visible and ultraviolet regions and infrared region as well. This calculator which is given here will help the researcher to find directly the energy gap Eg.

    ReplyDelete
  2. Kumaar Swamy Reddy B26 April 2017 at 11:46

    What if my sample has two absorption peaks or no peak at all? How do I calculate my bandgap?

    ReplyDelete
    Replies
    1. You should draw tauc plot for that

      Delete
    2. it means your sample is not single phase, its amorphous part shows one indirect band gap and partly crystalline pary has another direct band gap.You should report it as such. 2ndly might be your dopant is not uniformly distributed in the sample due due to low mol%

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    3. it means your sample is not single phase, its amorphous part shows one indirect band gap and partly crystalline part has another direct band gap.You should report it as such. 2ndly might be your dopant is not uniformly distributed in the sample due to low mol%

      Delete
  3. Vinil Namdev Jambhale5 October 2017 at 22:31

    How to calculate urbach energy from band gap.

    ReplyDelete
  4. I can't understand how to calculate FWHM using xrd. Can u explain briefly using xrd graph without using any software?

    ReplyDelete
    Replies
    1. Hi, How do I calculate the gap energy from XRD results?

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  5. Akash the FWHM is very easy by using origion software for your XRD spectra.when you draw your xrd data in origion then make one peak zoom go to analysis then peak and base line then multiple peak fitting then open dialog change the gauss to gaussian then click ok a side window will open then open fitting a full history of the peak will appear then you can find the FWHM value of your peak in paprameters.

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    Replies
    1. Hi, How do I calculate the gap energy from XRD results?

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  6. Why the absorbance decreases at shorter wavelength (200-217nm)?

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  7. Hi,
    1-open your XRD pattern by X'Pert High Score,
    2-push right click bottom on the pattern and then select search peaks.
    3-again push right click bottom on the pattern and choose the label peaks,
    4- active FWHM option,
    5- now you can see the FWHM value for each peak in your pattern.
    note that; in this method the FWHM unit shown in degree. if you want to calculate crystallite size or lattice strain, you should convert it to Radian.

    ReplyDelete
    Replies
    1. hey do you have link to download X'pert highscore ?

      Delete
  8. Mr. Sumit Ramdas Patil20 December 2018 at 17:35

    Actually I want to know about the reflectance mode bandgap calculation ?
    Please specify ?

    ReplyDelete
    Replies
    1. you write IH model in origin software and get band gap with absorption coefficient.

      Delete
  9. How to calculate band gap for solid sample? Plz answer

    ReplyDelete
    Replies
    1. Melody khao khud jaan jao😂😂😂

      Delete
    2. Use IH model on your PL data and calculate band gap with help of absorption coefficient using values of S between 2 to 8.

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  10. Great explanation of uv vis spectroscopy. It would be Helpful for many students

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  11. What is the formula for calculating bandgap from PL Spectra

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  12. How to calculate nanoparticles size through band gap energy

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  13. Very good app on mobile and can i download on laptab

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  14. Kindly attach Bandgap energy excell sheet.

    ReplyDelete
  15. very useful site, if i may ask, is their a way to calculate band gap energy of nanopowder from XRD data? thanks

    ReplyDelete
    Replies
    1. No you can't
      you can do it from the PL data only with help of absorption coefficient because your sample is opaque.

      Delete
  16. this calculation using tauc plot method?

    ReplyDelete
    Replies
    1. How to make tauc plot method to calculate band gap energy?

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  17. Thanks a lot. Really this is very helpful for me.

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  18. it helps me a lot (very useful). Thank you so much

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  19. How it differs from DRS (Diffuse Reflectance Spec.)????

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  20. how to calculate this optical band gap for porphyrins

    ReplyDelete

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