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Nano SPEAKs
Pakistan
Приєднався 27 лис 2017
This channel focuses purely on research for EVERY researchers. I am making Long Videos, Shorts Videos, and Writing Post to help the audience choose their best way of learning. The main focus is on the synthesis methods for nanomaterials (nanoparticles, nanofibers, nanorods, MOFs, Aerogel, layered and 2D nanomaterials, Graphene, and MXenes) and the Characterization techniques such as XRD, BET, XPS, SEM, EDS, TEM, SAED, UV-Vis, and PL.
In addition, special focus is on thesis | Dissertation writing, research objectives, problems statement, and scope of the study. There are quite interesting contents available on EndNote and Origin Pro, which is so helpful in writing Research Papers | Thesis | Dissertation.
There are handful videos on how to write a Review Paper, Review Article, which are quite helpful for every researcher.
If you find my videos and posts helpful, I would be very thankful to SHARE, LIKE, COMMENT on videos and SUBSCRIBE my channel.
Qamar Wali, PhD
In addition, special focus is on thesis | Dissertation writing, research objectives, problems statement, and scope of the study. There are quite interesting contents available on EndNote and Origin Pro, which is so helpful in writing Research Papers | Thesis | Dissertation.
There are handful videos on how to write a Review Paper, Review Article, which are quite helpful for every researcher.
If you find my videos and posts helpful, I would be very thankful to SHARE, LIKE, COMMENT on videos and SUBSCRIBE my channel.
Qamar Wali, PhD
Fundamental Principle of XPS
XPS is a surface analysis!
X-ray Photoelectron Spectroscopy (XPS) is a key and very important surface analysis technique. In this technique, an x-rays is simply bombarded on the sample, and the photoelectrons emitted from the core of the atom. The Kinetic Energy (KE) of the photoelectrons then detected by the XPS detector. Using the following equation, the Binding Energy (BE) can be calculated
BE = hv - KE - ϕspec
Where 'hv' is the x-rays energy (constant value), ϕspec is the work function of the spectrometer (a constant value). Therefore, the BE of the element can be calculated, which can reveal many important characteristics about the element. For instance, what element exists, what the atom or element bonded with, the chemical environment, oxidation states, whether the electrons removed or added to the atom.....
Question: Why is Studying Surface important?
Response: All materials contain surfaces, which interact with other materials. For instance, the key properties such as surface wettability, corrosion, adhesion, charge transfer, and CATALYSIS are all determined by surfaces, so surface analysis is important and XPS can be utilized to characterized the surfaces.
Question: What is Surface?
Response: A surface is an extremely thin layer, i.e., surface = 3 atomic layers (~1 nm). Size wise, the surface, ultra-thin film, and thin film are related by the following relation
*Surface* smaller than *Ultra-thin film* smaller than *Thin film*
Question: Why is XPS Surface Sensitive Technique?
Response: Approximately 95% of the photoelectrons are emitted from the ~10 nm depth surface. This is why XPS is termed as surface sensitive analysis. However, x-rays can penetrate to a few micro meter depths in the sample, but due to inelastic scattering and the smaller free mean paths of electrons, the photoelectron lost all of KE and can not reach the XPS detector
In XPS, x-rays completely transfer its energy to the core electron and there are Photogenerated electron, Auger electron, & XRF phenomena (this one is weaker and can not be considered). Therefore, the XPS spectrum contains only the photoelectron peaks and Auger electron peaks.
In the XPS spectrum, the number of electrons detected are plotted on the y-axis while the BE plotted on the x-axis.
Cheers!
Best luck!
X-ray Photoelectron Spectroscopy (XPS) is a key and very important surface analysis technique. In this technique, an x-rays is simply bombarded on the sample, and the photoelectrons emitted from the core of the atom. The Kinetic Energy (KE) of the photoelectrons then detected by the XPS detector. Using the following equation, the Binding Energy (BE) can be calculated
BE = hv - KE - ϕspec
Where 'hv' is the x-rays energy (constant value), ϕspec is the work function of the spectrometer (a constant value). Therefore, the BE of the element can be calculated, which can reveal many important characteristics about the element. For instance, what element exists, what the atom or element bonded with, the chemical environment, oxidation states, whether the electrons removed or added to the atom.....
Question: Why is Studying Surface important?
Response: All materials contain surfaces, which interact with other materials. For instance, the key properties such as surface wettability, corrosion, adhesion, charge transfer, and CATALYSIS are all determined by surfaces, so surface analysis is important and XPS can be utilized to characterized the surfaces.
Question: What is Surface?
Response: A surface is an extremely thin layer, i.e., surface = 3 atomic layers (~1 nm). Size wise, the surface, ultra-thin film, and thin film are related by the following relation
*Surface* smaller than *Ultra-thin film* smaller than *Thin film*
Question: Why is XPS Surface Sensitive Technique?
Response: Approximately 95% of the photoelectrons are emitted from the ~10 nm depth surface. This is why XPS is termed as surface sensitive analysis. However, x-rays can penetrate to a few micro meter depths in the sample, but due to inelastic scattering and the smaller free mean paths of electrons, the photoelectron lost all of KE and can not reach the XPS detector
In XPS, x-rays completely transfer its energy to the core electron and there are Photogenerated electron, Auger electron, & XRF phenomena (this one is weaker and can not be considered). Therefore, the XPS spectrum contains only the photoelectron peaks and Auger electron peaks.
In the XPS spectrum, the number of electrons detected are plotted on the y-axis while the BE plotted on the x-axis.
Cheers!
Best luck!
Переглядів: 124
Відео
Why is XPS called Surface Sensitive Technique?
Переглядів 102День тому
In XPS, surface sensitivity means how deep photoelectron can be generated and still escape from the sample without inelastic scattering. Using Beer’s law, it is observed that ~95% of the electrons will escape from a depth of ≤ 10 nm, refer to as information depth (sampling depth) for XPS. Because the path length of photoelectrons in solids is very small as compared to photons. Therefore, the de...
Why XPS is a Surface Sensitive Technique?
Переглядів 1014 дні тому
In XPS, surface sensitivity means how deep photoelectron can be generated and still escape from the sample without inelastic scattering. Using Beer’s law, it is observed that ~95% of the electrons will escape from a depth of ≤ 10 nm, refer to as information depth (sampling depth) for XPS. Because the path length of photoelectrons in solids is very small as compared to photons. Therefore, the de...
XPS - X-rays Photoelectron Spectroscopy || Surface vs. Ultra thin film vs. Thin film
Переглядів 1075 днів тому
XPS is a surface analysis! X-ray Photoelectron Spectroscopy (XPS) is a key and very important surface analysis technique. In this technique, an x-rays is simply bombarded on the sample, and the photoelectrons emitted from the core of the atom. The Kinetic Energy (KE) of the photoelectrons then detected by the XPS detector. Using the following equation, the Binding Energy (BE) can be calculated ...
Why XRD Peak intensity get smaller with increasing 2 theta (2Θ)
Переглядів 29020 днів тому
In XRD analysis, it is one the common question that why XRD Peak intensity get smaller with increasing 2 theta (2Θ) ? One line answer is, “Due to higher scattering probability”: At smaller 2θ (lower diffraction angles), the incident x-rays interact with a larger volume of the sample before being diffracted, which shows higher scattering probability. In addition, x-rays can interact with a great...
Secret Behind Bragg's law (nλ = 2dsinθ)- Reflection angle vs. Diffraction angle
Переглядів 226Місяць тому
*Reflection* and *Diffraction* are the two confusing words in XRD analysis & Bragg law (nλ = 2dsinθ). Let's explain it❗ Here, the focus is only on XRD analysis (Bragg law, nλ = 2dsinθ) Diffraction is more complex phenomena than the Reflection. Diffraction is sometimes also confused with Scattering. The diffraction is the special or sub-type of Scattering! ✅ NO 1:✍ ⇒ Reflection only takes place ...
Secret Behind Bragg's law (nλ = 2dsinθ) - Reflected angle vs. Diffracted angle
Переглядів 444Місяць тому
*Reflection* and *Diffraction* are the two confusing words in XRD analysis & Bragg law (nλ = 2dsinθ). Let's explain it❗ Here, the focus is only on XRD analysis (Bragg law, nλ = 2dsinθ) Diffraction is more complex phenomena than the Reflection. Diffraction is sometimes also confused with Scattering. The diffraction is the special or sub-type of Scattering! ✅ NO 1:✍ ⇒ Reflection only takes place ...
Secret Behind X-rays scattering by electrons - atoms - unit cells (Crystal) || XRD analysis
Переглядів 343Місяць тому
Structure Factor - Scattering of x-rays from electron ⟹ atom ⟹ unit cell - Contribution in XRD Peak intensity ✍🥀 Bragg’s equation (nλ= 2dsinθ) tells us about the peaks position (2θ). However, tells nothing about the peak intensities. The intensities of the XRD peaks depend on many factors but here we only discuss the “Structure factor” When x-rays shine on a crystal can scatter in three ways: A...
Secret Behind X-rays scattering from electrons - atoms - unit cells (Crystal) || XRD Analysis
Переглядів 353Місяць тому
Structure Factor - Scattering of x-rays from electron ⟹ atom ⟹ unit cell - Contribution in XRD Peak intensity ✍🥀 Bragg’s equation (nλ= 2dsinθ) tells us about the peaks position (2θ). However, tells nothing about the peak intensities. The intensities of the XRD peaks depend on many factors, but here, we only discuss the “Structure factor” When x-rays shine on a crystal can scatter in three ways:...
Why is XRD Peaks Shift due to Doping
Переглядів 274Місяць тому
How is the XRD peak shift due to doping? Doping - Introduction of impurities into a crystal lattice can cause to expand or contract the host lattice volume - changes lattice parameters or produce strain within the material - leads to a significant shift in the XRD peaks. Due to doping, changes in crystal structure, change the lattice parameters, or strain within the material. Here are the main ...
How is XRD Peak Shift with Temperature
Переглядів 262Місяць тому
Crystallite XRD vs. Liquid/Amorphous/Polymer XRD
Переглядів 63Місяць тому
For crystalline solid, the curve of scattered intensity vs. 2θ is almost zero everywhere except at certain angles where sharp peaks occur. Here, at these particular angles, the Bragg’s law, λ = 2dsinθ satisfied, and PEAKs appeared. Liquid, Amorphous or Polymer solids structures are characterized by an almost complete lack of periodicity and a tendency to "order" only in the sense that the atoms...
Crystalline XRD vs. Monatomic gas XRD
Переглядів 157Місяць тому
For crystalline solid, the curve of scattered intensity vs. 2θ is almost zero everywhere except at certain angles where sharp peaks occur. Here, at these particular angle, the Bragg’s law, λ = 2dsinθ satisfied. The monatomic gases, which have no structural periodicity whatever; in such gases, the atoms are arranged in a complete random order, and their relative positions change constantly with ...
Why 2θ in XRD graph instead of θ?
Переглядів 160Місяць тому
Why 2θ in XRD? Two types of goniometers used in XRD analysis: 1- θ:θ Scan 2- θ:2θ Scan This post explains why there is 2θ in XRD technique with the help of *θ:θ Scan* setup. *θ:θ Scan*: In a θ:θ instrument, the sample is *FIXED* and the x-rays tube rotates at a rate θ°/min (clockwise) and the detector rotates at a rate of θ°/min (anti-clockwise), see the video. Here, in this case, we usefully s...
How XRD Peak Intensity depends on Atoms Position
Переглядів 164Місяць тому
How does peak intensity depend on atoms positions (x, y, z) in XRD analysis? OR Positions of the atoms in the unit cell affect the intensities in XRD analysis!. How? Let explain this! We consider two unit cells (shown in the attached images), i.e., Base centred orthorhombic & Body centred orthorhombic. Here in both cases, TWO atoms per unit cell, one atom from the corner, and other atoms are th...
I am just a PhD student. Can I publish my own work without my supervisor? Does it cost a lot of money?
Yes sure. You can publish as many as papers you have. There are two types of publications options. 1) Open access and 2( Subscription one. Please watch videos on my channel
sir will you pls explain why the broadening in peaks happens for nano material
I have already explained in the video and I also kept the text in the description, BUT you don't read it 😒 How the XRD peaks broaden as the size of the crystallite or grain or particles getting smaller? As the size of the material decreases from bulk (micro meter size) to nano (1-100 nm), the XRD peak starts broadening. This broadening is just like the amorphous materials. The x-rays realized the nanomaterials are just like the amorphous materials. In such a scenario, the XRD technique becomes difficult to analyze the nanomaterials of small size as the scattering of x-rays in many directions. The XRD technique becomes difficult to analyze the sample with crystallite size / particle size below than 5 nm as the peaks broad and low signal to noise ratio. Importance: This broadening of peaks has a significant importance in nanomaterials characterizations. For instance, if TEM shows the particle size ~ 10 nm BUT the XRD of the same sample shows SHARP peaks, then there is discrepancy. It means that the majority of the particles in the sample are not in the ~10 nm range, BUT rather large in size.
What if we run the same process only except adding A in the process? What will happen then?
Useless
How useless? I have just shown ONE method for Figure insertion to the MS word document. There might be other ways, but this works well. If you know other methods, please let's us know. Thanks for your comment.
Dear Prof. Thank you for sharing your expertise all the videos on your channel are very educational and incredibly useful. Keep up the fantastic work, cheers
Nice to hear from you. Many thanks for watching my content on You tube. You are welcome!
Maaaaaaaany thanks
I want to ask question related to XRD...what are miller indices and what thing they tell about unit cell?
Miller indices are notation used in crystallography to show orientation of planes in crystal lattices. It is usually represents by three integers such as h, k, and l such as (hkl) = (100), (110), (200), ) (101), (111)........ In simple words, miller indices show the number of atoms exist in the x, y and z directions. Question: What is Plane in crystallography or in crystal structure? Answer: Plane means atoms arranged in order just like the mirror. When the x-rays shine on the plane, the x-rays will reflect (diffract or scatter), and the internal crystal will reveal. Just like the mirror, when we shine light, the light reflect at a specific point, now if the mirror is broken, the reflect light will not focus on a specific point. PS: I would appreciate if you ask relevant question to the video. As I have a lot of videos on XRD analysis. Many thanks for the comment and wish you best luck!
Seriously, these are life savers concise, digestible, Awesome job!!! Thank you so much for this!!! Only note is I wish there were subtitles when I click the CC
Many thanks for the nice words. Sure, I will improve the contents and incorporate your other suggestions. ❤️
Dear Sir, I'm watching Thank you very much for uploading xps video
Great to hear. Please do comment if you have any confusion.
Dear Prof. thanks a lot
What can SEM-EDS analysis of microplastic samples interpret?
*SEM* just reveals the morphology of the sample. For instance, what is the shape, size, height, diameter, radius of the sample, whether the sample is made up of nanoparticles, nanorods, nanosphere, whether the surface is rough or smooth...... While EDS is embedded with SEM used for elemental analysis. For instance, it reveals what the constitutes of the sample are. In your case, there might be carbon, hydrogen, oxygen, nitrogen, chlorine, sulfur, etc... The EDS provides information in the form of wt% and atm% of the elements that exist in the sample.
@@qamarwali Thank you so much for clarification, Sir
Need to contract with professor??? They gave details link about professor and his projects. So phd applicant need to sent email to professor or not???
First , you must send an email to a professor. If he or she agrees, then start applying.
@@qamarwali ok thanks 😊
thank you from india
Welcome dear 😘
@@qamarwali kindly make a video on end note for reference sir❤
@naveen7491 go to the EndNote playlist in my channel. There are a lot of videos
Very informative. appreciated. thank you, sir
Welcome! I am happy you like it
Great work sir. Very informative but i would request you to make a video on how to determine the porosity and volume of nanoparticles using BET analysis? Is there a separate profile along with the original results or we calculate them through some equations from the given data the same way we calculate particle size and other parameters from X ray analysis? I would be grateful if you could please elaborate it here in a reply! Regards
Many thanks for the comment. In my case, the pore size and pore volume were already given in the raw file received from BET analyzer. Anyway, I will see to make another video on the said topic. Best luck!
Can u explain me energy density and powerr density of battery with mathematical formulas
Energy density = Wh/m³ or Wh/kg while Power density = Wh/m³ x Voltage Or Wh/kg ³ x Voltage. FYI, for better understanding, just download good review paper on Battery or supercapacitor and read it.
Sir can you please invite me to create a researcher gate account
Sure, but I don't know how it works. I think simply get an email id from your institute (IT center) and create your RG profile. Every university/organization has the ICT office and they are bound to provide the email id end with @....edu... to every individual (students/staff/faculty) but they usually refused to do so!.
شما چرا نظرات گوشت نمیکنید چرا نمیبینید در ایران در برنامه دارم دزدی میکنن وکارای دیگه.من مجبورم به پلیس اینترپل گزارش بدم اگه به همین وضع ادامه و ترکی صحبت کنید آقای محترم
Thanks for the comment. Actually I don't understand the language you used and it would be great to comment in English, please. Good luck!
Good information
Thanks 😊
Appreciate Dr for excellent explanation. Could you please share the specific reference for evidence this clarification thanks
Most of the posts and videos on XRD taken from the book title *Elements of X-Ray Diffraction* by B.D. Cullity & S.R. Stock. It is free available. Anyways some contents of my videos or post MAY NOT be found in this book and I just used my concepts or taken some concepts from RG. After reading and clearing my concepts, I made videos. I am very happy to receive your comments if you have any concerns. I am here to help and discuss to the best of capability if any queries related to the topic. Wish you best of luck!
@@qamarwali highly appreciate Dr that’s your kindness, Dr did you work on perovskite materials depositions?
@goldenwing5375 welcome. I worked little during my PhD. in 2015, but later on ,I could not find any opportunities to work on . I did write many reviews on pervoskites solar cells.
@@qamarwali many thanks Dr for swiftly reply, I have issue in the deposition when deposit perovskite solution on substrate during spin coating process the perovskite solution doesn’t dry well and stay a little bit wet , could please advice me what is the problem or recommend me what I have to do for modification the spin coating process , thank you
@goldenwing5375 where are you working now a days ? I have a friend working in MUST, Kashmir, and we can discuss it with him. Because he is involved in this field.
Hello, Dr. Qamar Wali, yet another great video for the beginners like me, keep up the good work. Lot of prayers for you.
I'm glad to hear from you. Many thanks for your comment and nice words 👍
Why oxygen is present in large amount?
Because most of the oxygen is added when we do calcination in the oven. For instance, if I am making TiO2, I have to do thermal annealing, and the oxygen basically comes during this process. There might be other reasons
@@qamarwali Thank you Sir
Hello, Professor, can you help me by asking questions about the Métal organic framework, because my memorandum talks about this topic?
I am not that expert in MOF, but I can recommend some quality research papers that can help you understand the basic concepts and advances...
Thanks
Sir, really very beneficial for student
Many thanks 😊 Yeah, I am trying to clear these concepts.
Can someone tell how he has added table in that plot??
You can do it in PPT or Orgin Pro.. You can also do it using Photoshop or Canva..... There are many options, but I recommend using PPT as it is very basic and simple.
@@qamarwali in ppT we can’t group it right? So, later on will it move from its place?
@robamatariq8485 Look, just insert one image and then another image on the top of it. Just export it as an image. How? Just save as the ppt and change the ppt to PNG or JPG options and save that slide only. Then, insert this image into your Word document. Another way is just group it and copy and then past it in the word as image...... I have made a video on it in the playlist *how to write reviews paper* just watch that. Let me know if you still need help
@@qamarwali thanks
Sir nano materials mai dissertation bana nhi koi problem suggest kar dijaye ?
People write dissertations at the END of the study. First of all, you have to do a comprehensive literature review. From that literature, you will find the gap, problem or issue. Now use a systematic methods to address that issue or problem...... Then you will dissertation what you have done..... I hope it is clear to you
I have 20+ pages review paper on biomedical filter, but for publishing i am confused pls guide me for fast publication in scopus or sci indexed
Just use *Elsevier journal finder* . It will provide you the most relevant journals You need to paste your title and abstract there
Where i send my review article for good publishing
Just use Elsevier journals finder Write it in Google and you will see the link
Loved it
hello!! i’d like to say that is a very good video!! i have a question: in the case of phosphorescence PL type, how the relaxation can occurs? the material has to be stimulated again or simply decay lower than the fluorescence? i mean this because of “optically stimulated luminescence“ which is caused by previous irradiation, but i’m this case leads to a anti stokes emission! thanks for the content !!!
In fluorescence, the molecule quickly re-emits within a very short (nanoseconds), while phosphorescence involves a longer timescale for light emission. No extra stimulation is required. These both can occurs simultaneously BUT one has to use sophisticated machine to measure these two process at the same time. In Raman spectroscopy, when light absorbed by molecules, the following phenomenon occurs. *Rayleigh Scattering:* When the emit light has exactly the same frequency, energy, wavelength or color. This is due to the coherent scattering (Elastic scattering). For instance, > 99% scattered photons demonstrate the "Rayleigh effect" *Raman Scattering (Stokes & Anti-Stokes)* Raman scattering is based on the inelastic scattering and overall, < 1% of scattered photons demonstrate the "Raman effect" *Stokes Scattering:* When the emit light has lower energy than the incident photons and most of the Raman scattering composed of the Stokes scattering. *Anti- Stokes Scattering:* When the emit light has higher energy than the absorbed photons and this is very rarely occurring phenomena as the molecule are required to be higher vibrational state which is very rare. According to Boltzmann distribution. To sum up, the Rayleigh scattering >>>> Stokes scattering > Anti-Stokes scattering ....
Many thanks for the nice words. I am sorry if I could not answer exactly. Wish you good luck!
Outstanding lecture ❤
Many thanks 😊