Please check the video description, links to the bibliography are being provided there. The data behind these plots (images) have also been provided in the video description. Thanks
Sorry, I did not find the bibliography, just the link to the originlab data. I mean any book or article that explains this topic for me to cite in my dissertation. Thanks again. @@SAYPhysics
The calculation of Urbach energy from UV-Vis absorbance data has been explored in various studies. Paleari 2007 (DOI: 10.1063/1.2794429) found that the Urbach energy values in fluorine-modified amorphous silica ranged between 50 and 66meV, indicating a reduction of dynamical disorder. Rai 2013 (DOI: 10.1063/1.4801900) analyzed the Urbach effect in undoped ZnO thin films, attributing it to impurities, structural disorders, and electron-phonon interaction. Croll 2002 (DOI: 10.1002/1521-3900(200209)187:13.0.CO;2-1) used UV spectroscopy to calculate the effective irradiation dosage during weathering, noting a non-linear relationship between UV absorption and damaging radiation. Sadigh 2011 (DOI: 10.1103/PHYSREVLETT.106.027401) conducted first-principles calculations of the Urbach tail in the optical absorption spectra of silica glass, confirming the exponential tails near the fundamental absorption edge. Thanks
Thank you for your kind words! Yes, it is possible to determine Urbach energy from DRS data. The DRS data, often converted to absorbance through the Kubelka-Munk function, can provide the absorption edge region needed for Urbach energy calculation. By plotting the natural logarithm of the absorption coefficient (or Kubelka-Munk function) against photon energy, you should be able to extract the Urbach energy as the inverse of the slope in the exponential tail region.
@@SAYPhysics Alright Sir, Thanks alot Sir, Thats what i have done exactly however as i was not sure about that either we can do it or not. Because their is an inverse realtion between the energy band gap and the Urbach Energy so it can be used as an explination parameter as well.
Exactly! The inverse relationship between band gap and Urbach energy can indeed help explain material disorder. Using DRS data for Urbach energy is valid, and the trends with band gap can provide useful insights into the structural and electronic disorder. Glad to hear you’re on the right track!
Calculating Urbach energy from UV-Vis reflectance data is possible but less straightforward than using absorbance data. Reflectance can be converted to absorbance using the Kubelka-Munk function or similar models. The accuracy depends on the reliability of this conversion and the quality of the reflectance data. Direct absorbance measurements are preferred for higher accuracy and simpler interpretation. Thanks
@@SAYPhysics Thank you sir. Using the DRS technique, I got Reflectance data. Using Kebelka-Munk function, can I calculate the absorption coefficient and use it in Urbach energy calculations?
Hi Professor, nice tutorial!!!! in the fitting results, there are two intercept values, one is "x intercept" and another is "intercept". What does the "intercept" mean? (I assume if we have y=a+bx, the "X intercept" is the "a" and "slope" is the "b")
Thank you for your positive feedback on the tutorial, I'm glad you found it helpful! When the slope (b) is positive and the line intersects the x-axis (i.e., the x-intercept), it implies that the y-intercept must be negative. Conversely, if the slope is negative and the line intersects the x-axis, then the y-intercept will be positive. This relationship is a fundamental property of linear functions.
We don't know this earlier unless the literature provides some information. When we do calculate it, we check whether it's a DB or IDB material. Thanks
Thanks for the appreciation dear. In the video description, I have provided the reference. I'll cover magnetic characterizations as well in future, IA.
THANK YOU SO MUCH
You're welcome dear
Hi! Can you tell where are these images from? Or indicate any bibliography to study these concepts? Thank you, very much!
Please check the video description, links to the bibliography are being provided there. The data behind these plots (images) have also been provided in the video description. Thanks
Sorry, I did not find the bibliography, just the link to the originlab data. I mean any book or article that explains this topic for me to cite in my dissertation. Thanks again. @@SAYPhysics
Or the source of figures in time 0:55
The calculation of Urbach energy from UV-Vis absorbance data has been explored in various studies. Paleari 2007 (DOI: 10.1063/1.2794429) found that the Urbach energy values in fluorine-modified amorphous silica ranged between 50 and 66meV, indicating a reduction of dynamical disorder. Rai 2013 (DOI: 10.1063/1.4801900) analyzed the Urbach effect in undoped ZnO thin films, attributing it to impurities, structural disorders, and electron-phonon interaction. Croll 2002 (DOI: 10.1002/1521-3900(200209)187:13.0.CO;2-1) used UV spectroscopy to calculate the effective irradiation dosage during weathering, noting a non-linear relationship between UV absorption and damaging radiation. Sadigh 2011 (DOI: 10.1103/PHYSREVLETT.106.027401) conducted first-principles calculations of the Urbach tail in the optical absorption spectra of silica glass, confirming the exponential tails near the fundamental absorption edge. Thanks
I have taken these images from the Google Images. Thanks
Dear Sir, Thank you very much for such a nice explination. Is it possible to measure the Urbach Energy for a DRS spectra
Thank you for your kind words! Yes, it is possible to determine Urbach energy from DRS data. The DRS data, often converted to absorbance through the Kubelka-Munk function, can provide the absorption edge region needed for Urbach energy calculation. By plotting the natural logarithm of the absorption coefficient (or Kubelka-Munk function) against photon energy, you should be able to extract the Urbach energy as the inverse of the slope in the exponential tail region.
@@SAYPhysics Alright Sir, Thanks alot Sir, Thats what i have done exactly however as i was not sure about that either we can do it or not. Because their is an inverse realtion between the energy band gap and the Urbach Energy so it can be used as an explination parameter as well.
Exactly! The inverse relationship between band gap and Urbach energy can indeed help explain material disorder. Using DRS data for Urbach energy is valid, and the trends with band gap can provide useful insights into the structural and electronic disorder. Glad to hear you’re on the right track!
How can we calculate Urbach energy from Reflectance data?
Thank you for your informative videos. 🙏👌
Calculating Urbach energy from UV-Vis reflectance data is possible but less straightforward than using absorbance data. Reflectance can be converted to absorbance using the Kubelka-Munk function or similar models. The accuracy depends on the reliability of this conversion and the quality of the reflectance data. Direct absorbance measurements are preferred for higher accuracy and simpler interpretation. Thanks
@@SAYPhysics Thank you sir.
Using the DRS technique, I got Reflectance data. Using Kebelka-Munk function, can I calculate the absorption coefficient and use it in Urbach energy calculations?
To calculate the refractive index, we apply the law of bandgap and do not plot urbach energy?
I'm not getting your question, would you please rephrase or elaborate? Thanks
THANK YOU SO MUCH SIR😭🫡
You're welcome dear..
Hi Professor, nice tutorial!!!! in the fitting results, there are two intercept values, one is "x intercept" and another is "intercept". What does the "intercept" mean? (I assume if we have y=a+bx, the "X intercept" is the "a" and "slope" is the "b")
Thank you for your positive feedback on the tutorial, I'm glad you found it helpful! When the slope (b) is positive and the line intersects the x-axis (i.e., the x-intercept), it implies that the y-intercept must be negative. Conversely, if the slope is negative and the line intersects the x-axis, then the y-intercept will be positive. This relationship is a fundamental property of linear functions.
Extremely helpful. THank you for making a video on this.
Glad it was helpful!
sir we plot graph between log of alpha and energy or natural log of alpha and energy
Log of alpha vs energy. Thanks
@@SAYPhysics thanks sir
Sir, when should we calculate direct band gap and when should we calculate indirect band gap?
We don't know this earlier unless the literature provides some information. When we do calculate it, we check whether it's a DB or IDB material. Thanks
Sir if a graphs dont have any linearity then is it possible to find out these values?
If it's a modified material, it must have Eu or otherwise. Thanks
sir how to calculate dielectric relaxation time from UV data
You will find some literature on it. However, I've not yet made a tutorial on it. Thanks
Thank you
Welcome dear
Welcome dear
When it's necessary to calculate Urbach energy?
When a material is modified such that interband levels are introduced, we calculate Urbach energy to assess the impurities role. Thanks
Best way
Thanks dear
Thank you sir for the nice illustrations
I hope if you kindly give some references links
Also I'm interested in magnetic properties
🙏🙏🙏
Thanks for the appreciation dear. In the video description, I have provided the reference.
I'll cover magnetic characterizations as well in future, IA.
@@SAYPhysics Many thanks sir
Jazaka Allahu khira
You're welcome dear