@@SAYPhysics Your videos are beneficial for my current manuscript, based on the synthesis and characterisation of metal oxide nanoparticles. I'll keep in touch with you.
Thank you for your explanation. I just have one more question. If my material is direct, should I use (F(R)hv)2 or (F(R)hv)1/2? It should be the former one according to the absorbance video but there is no specific explanation in the reflectance one. It should be the same right? Thank you!
The bandgap seems to be wrong because the origin of the vertical axis has not been set at zero. Vertical axis MUST start from zero. Otherwise the tangent line intersects the horizontal (eV) axis at a point less than the actual bandgap.
You're principally right, and in my case thee difference isn't more than 0.01 eV However, for a simplest case this is true only. In this playlist, I have a bunch of videos on the brandgap, you may watch them to get idea about some complex cases.Thanks
In UV-Vis spectroscopy, direct bandgap materials typically exhibit sharp absorption peaks, while indirect bandgap materials show broader absorption bands. By analyzing the shape and intensity of the absorption spectrum, along with theoretical modeling, you can determine whether the bandgap is direct or indirect. Additionally, plotting the absorption coefficient versus photon energy can help identify the nature of the bandgap. That's, we will check in which case a steep knee is formed. If for both 1/2 and 2, a steep knee is formed, it will mean it's a quasi band gap ie both direct and indirect. Thanks 😊
since both the direct and indirect bandgap looks the llinear you concluded that this is qusai direct bandgap then use indirect bandgap. Is this always true where when the direct and indirect looks the same linear you use indirect bandgap?
In general, when both direct and indirect bandgap data appear linear, it's safer to use the indirect bandgap for calculations. This is a common practice to ensure more accurate results in cases of ambiguity. Thanks
When we're only to decide about the location of a peak or its shifting, it's better to normalize the KM values. In the case of intensity discussion, we avoid to normalize as the data loses its importance then. Thanks
In addition to my explanation in the beginning of the tutorial, let me add that K is the absorption coefficient, and S is the scattering coefficient. However, due to the difficulty in measuring the absolute reflectance R∞, in practice, the comparative reflectance r∞ with respect to a standard powder of which K is near zero (0) in the actual measurement range. Thanks
@@SAYPhysics How absorption co efficient have unit per meter? If this is from R . Then R is simple the ratio of reflectance fromt the sample to standard. So it should be unitless.
@areejfatima2807 Absorption Coefficient (α) is measured in units of cm-1. This is used when dealing with the Beer-Lambert Law in contexts where concentration is not expressed in molarity. It's a measure of how much light is absorbed per unit path length. Thanks
You're using an old version. The f(x) insertion is available in version 9.0 and above. However, you need not to worry that I have already uploaded a video on how to legally install the latest version of OriginLab. Thanks ruclips.net/video/LamBqZbS3F0/видео.html
Hello, thanks for the video. Is this method applicable for specular reflectance? Also, From the tauc plot (alpha h v)2 vs (hv), how can we measure the energy band gap if we have multiple peaks? I mean it’s difficult to choose a point to extrapolate if we have multiple peaks. So, how can we decide?
Thanks for the appreciation dear. In multiple peaks, you may choose the first one as a band edge. It's a diffused reflectiance . If your material is a modified perovskite, it possess different bands corresponding to different energies.
@@SAYPhysics If I choose first one as the band edge, it results in very low band gap. I work on ferroelectric (PLZT) thin films for photovoltaic applications. Yes, it’s a perovskite material. I could measure the specular reflectance on my films using UV-VIS. Is this method applicable only for diffuse reflectance?
@@SAYPhysics If it has different bands corresponding to different energies, then how can we put the accurate band gap? The PLZT material has a bang gap (3-3.5 eV). I was considering the peak within that range. But I am not sure if it’s the right way to do. I can share the data with you if you want to look at it.
For such materials, you can't use the familiar R+A+T=1 equation to get reflectance (which is specular in nature). You need to have DRS data, and then use the guidelines provided in this video. Thanks
Thank you for watching the video! I've included all the necessary details and calculations in the video description. You can find an Excel template there that demonstrates how to calculate the band gap energy from UV-Vis reflection (DRS) data, including the absorption (A) values. Please check it out, and if you have any further questions, feel free to ask. Thanks again for your interest.
Yes. Check the following playlist which has some videos on this. Thanks Bandgap Calculation in Origin: ruclips.net/p/PLeWSImvDbplfORnYYdjb0DLiLpyi7VWY1
@@SAYPhysics but there is no video in which absorbance A is converted into Reflactance R... in K-M function the parameter is R which means we need reflactance.. but issue is that I have absorbance vs wave length data
The video explains how to get values for explaining/analyzing your data. I'll soon explain in another video how to interpret UV-Vis data, once all the values extraction is completed. Thanks
Take the data in a separate column and apply the normalization as 0-1 or 0-100. Inside my playlist, You'll find some videos on the normalization. Thanks
Take the data in a separate column and apply the normalization as 0-1 or 0-100. Inside my playlist, You'll find some videos on the normalization. Thanks
Thank u so much, dear sir. You have set aside a few minutes for the day's task.
Thanks for the appreciation dear 😊
You have helped me in my graduation project. God bless You.
Thanks for the acknowledgement. Please share it with others as well.
Thanks, Dr. Shahid Ali Sir for another useful video on bandgap calculation.
Thanks dear for being in touch.
@@SAYPhysics Your videos are beneficial for my current manuscript, based on the synthesis and characterisation of metal oxide nanoparticles. I'll keep in touch with you.
Yes, sure. You're welcome
Thank you so much. Very good explanation.
Thanks for the appreciation 😊 and you're most welcome dear.
Excellent presentation. Thanks for sharing and deciding your time to learn us. God bless you. 🙏🌸
Thanks for the appreciation dear. I really enjoy doing these. Aameen
Thanks. The minimum y-axis should be 0, then the extrapolation line is correct.
Yes, you're right, provided offsets are not involved. Thanks
Thank you for your explanation. I just have one more question. If my material is direct, should I use (F(R)hv)2 or (F(R)hv)1/2? It should be the former one according to the absorbance video but there is no specific explanation in the reflectance one. It should be the same right? Thank you!
Nice, elaborated, and to the point.
Thanks for the appreciation dear
The bandgap seems to be wrong because the origin of the vertical axis has not been set at zero. Vertical axis MUST start from zero. Otherwise the tangent line intersects the horizontal (eV) axis at a point less than the actual bandgap.
You're principally right, and in my case thee difference isn't more than 0.01 eV However, for a simplest case this is true only. In this playlist, I have a bunch of videos on the brandgap, you may watch them to get idea about some complex cases.Thanks
thank you very much
You're welcome dear
Wonderfull Sir, Sir kindly make vedio to calculate Response and Recovery time, and hysteresis loop calculations.
Thanks for the appreciation dear. Sure, I'll do so as per my schedule tutorials.
@@SAYPhysics thank you sir waiting for your lecture
Sure dear. Thanks
Sir well explained 🤗❤
Thanks dear
My plxr sir ❤
Can you explain the extra drop in ahv1/2 and ahv2 on higher hv value?
I didn't get it
Would you please let me know the exact location of the video so that I can respond accurately to that. Thanks
How can we find which band gap is correct( direct or indirect) ??
In UV-Vis spectroscopy, direct bandgap materials typically exhibit sharp absorption peaks, while indirect bandgap materials show broader absorption bands. By analyzing the shape and intensity of the absorption spectrum, along with theoretical modeling, you can determine whether the bandgap is direct or indirect. Additionally, plotting the absorption coefficient versus photon energy can help identify the nature of the bandgap. That's, we will check in which case a steep knee is formed. If for both 1/2 and 2, a steep knee is formed, it will mean it's a quasi band gap ie both direct and indirect. Thanks 😊
since both the direct and indirect bandgap looks the llinear you concluded that this is qusai direct bandgap then use indirect bandgap. Is this always true where when the direct and indirect looks the same linear you use indirect bandgap?
In general, when both direct and indirect bandgap data appear linear, it's safer to use the indirect bandgap for calculations. This is a common practice to ensure more accurate results in cases of ambiguity. Thanks
some people asking about the normalizing of K-M functions in comments, why do we need to normalise and when to.
When we're only to decide about the location of a peak or its shifting, it's better to normalize the KM values. In the case of intensity discussion, we avoid to normalize as the data loses its importance then. Thanks
What does F(R) means physically? It's the ratio between k/s but, what is that?
In addition to my explanation in the beginning of the tutorial, let me add that K is the absorption coefficient, and S is the scattering coefficient. However, due to the difficulty in measuring the absolute reflectance R∞, in practice, the comparative reflectance r∞ with respect to a standard powder of which K is near zero (0) in the actual measurement range. Thanks
@@SAYPhysics If F(R) = K/S , Then how are you putting cm with eV in the unit on y axis.
In the first 5 min part of the tutorial, I'm explaining all this. If your confusion yet continues, let me know, I will elaborate it further. Thanks
@@SAYPhysics How absorption co efficient have unit per meter? If this is from R . Then R is simple the ratio of reflectance fromt the sample to standard. So it should be unitless.
@areejfatima2807 Absorption Coefficient (α) is measured in units of cm-1. This is used when dealing with the Beer-Lambert Law in contexts where concentration is not expressed in molarity. It's a measure of how much light is absorbed per unit path length. Thanks
Hello, i am using origin 8.5... In this how to insert f (x) row??
You're using an old version. The f(x) insertion is available in version 9.0 and above. However, you need not to worry that I have already uploaded a video on how to legally install the latest version of OriginLab. Thanks
ruclips.net/video/LamBqZbS3F0/видео.html
Waiting for QM lectures
Which subject u will upload in this semester
In a month IA, we'll start uploading from Lecture 51 onward, as per Griffiths book content. Thanks
@@SAYPhysics also upload another course in parallel to QM
Yes, I'll in relativity, IA
Hello, thanks for the video. Is this method applicable for specular reflectance? Also,
From the tauc plot (alpha h v)2 vs (hv), how can we measure the energy band gap if we have multiple peaks? I mean it’s difficult to choose a point to extrapolate if we have multiple peaks. So, how can we decide?
Thanks for the appreciation dear. In multiple peaks, you may choose the first one as a band edge. It's a diffused reflectiance . If your material is a modified perovskite, it possess different bands corresponding to different energies.
@@SAYPhysics If I choose first one as the band edge, it results in very low band gap. I work on ferroelectric (PLZT) thin films for photovoltaic applications. Yes, it’s a perovskite material. I could measure the specular reflectance on my films using UV-VIS. Is this method applicable only for diffuse reflectance?
@@SAYPhysics If it has different bands corresponding to different energies, then how can we put the accurate band gap? The PLZT material has a bang gap (3-3.5 eV). I was considering the peak within that range. But I am not sure if it’s the right way to do. I can share the data with you if you want to look at it.
@@SAYPhysics please respond.
For such materials, you can't use the familiar R+A+T=1 equation to get reflectance (which is specular in nature). You need to have DRS data, and then use the guidelines provided in this video. Thanks
How can you calculate energy in ev where is the absorption A?
Thank you for watching the video! I've included all the necessary details and calculations in the video description. You can find an Excel template there that demonstrates how to calculate the band gap energy from UV-Vis reflection (DRS) data, including the absorption (A) values. Please check it out, and if you have any further questions, feel free to ask. Thanks again for your interest.
what the significant different ahv2 and ahv1/2, sir?
This decides about the directi and indirect bandgaps, respectively. Thanks
good.. dear I have absorbance data from uv spectroscopy... can I convert this data into reflactance and solve it for and gap
Yes. Check the following playlist which has some videos on this. Thanks
Bandgap Calculation in Origin: ruclips.net/p/PLeWSImvDbplfORnYYdjb0DLiLpyi7VWY1
@@SAYPhysics it is very well explained.. but sir actually I have absorbance data and I want to convert it into reflactance... is it possible or not?
I told you Yes. With the help of K-M function, you can do so, as explained in these videos. Thanks for the appreciation 😊
@@SAYPhysics but there is no video in which absorbance A is converted into Reflactance R... in K-M function the parameter is R which means we need reflactance.. but issue is that I have absorbance vs wave length data
sorry for so many questions
after processing the data how do I analyze the data
The video explains how to get values for explaining/analyzing your data. I'll soon explain in another video how to interpret UV-Vis data, once all the values extraction is completed. Thanks
How can I normalize the K-M function?
Take the data in a separate column and apply the normalization as 0-1 or 0-100. Inside my playlist, You'll find some videos on the normalization. Thanks
Plz sir start QM lectures my 7th semester is start
From tomorrow IA we'll start uploading relativity lectures and then in a month the QM. Thanks
where does 1240 come from?
It's based on some calculations which I have done in detail in the following video tutorial. Thanks
ruclips.net/video/LLESVSsZmlg/видео.html
How can I normalize the K-M function?
Take the data in a separate column and apply the normalization as 0-1 or 0-100. Inside my playlist, You'll find some videos on the normalization. Thanks
@@SAYPhysics Thank you, although I need a procedure for the normalization of K-M function with respect to Reflectance for the transmittance obtention.
Right. You can send me your data on sayphysics@gmail.com if the videos are not helping you. Thanks