Search results for query: *

I have three questions regarding the material Gallium Oxide. I was reading in several articles and they introduced its structure as it has monoclinic structure and it consists tetrahedral and octahedral structures in it. What I can't understand I can connect this structure to the chemical...

What is the difference between the approaches of Einstein, Debye and Peierls regarding the heat transfer?!

In general, in the paper Casimir assumes that between the boundaries of a crystal the heat transfer can be imagined as electromagnetic radiation between two hollow bodies connected by a tube (at least this what I understood from his approach), I'm reading about Casimir limit (Ballistic heat...

Thank you all for the answers, it directed me and explained a lot of things to me. :) Sure if I have further questions so I will post it here ;)

Hello Everyone! I read about the function of the ruby laser which made from ruby crystal and has three energy levels. There is radiationless transition to what so called metastable level and then the electrons there stimulated to transit to ground energy state. The question is: does this...

I still here :) thank you so much for answering the thread :)

The link is really useful thank you :)

Thank you so much for the answer :) , yes I'm talking about crystals and nothing biological :D Then the coalescence which process it describes?

Im bit confused about what is exactly the difference between the terms, which process every term describes ?

Why J-aggregation has red shift and H-aggregation has blue shift what is the physics behind it? And the second question is does J-aggregate can makes with another J-aggregate H-aggregate?? (I'm new in this topic)

Thank you for the answer :)

How the number of the particles in a solution increase the probability to get adsorption on a surface? which physical terms explain this? For example when I increase the concentration of molecules in a solution I can see that the adsorption and the aggregation on the surface happen.

How a high mobility of particles over surface cause to aggregation, the professor in the class said that "high mobility causes to local equilibration and thus to a compact aggregation".. which I didn't understand..! What does he mean about local equilibration and how all connect to each other?!

It is a solvent which contains MnTPP molecules and the solution is toluene (the "liquid" that was mentioned above)... yes it is thin fiber embedded in a glass so it is in the same plane with the surface of the glass... the molecules (MnTPP) aggregated over the fiber (the thin fiber)... (The...

I poured a droplet that has 1.55 refractive index (RF) over a fiber that has core and cladding with (RI) 1.45 and 1.4 respectively, and I the molecules aggregated over the fiber, known that because the refractive index of the liquid is higher than of than of the core or the cladding a leakage of...

Yes I mean about the transverse Gaussain modes... when I look at the answers I see ##e^{-\frac{x^2+y^2}{w_0}}\times F(x,y)## where ##F(x,y)## can be bessel or Hermite... So my question is: can one look at this as the Gaussian divided in the space (yellow in the image above), or every mode by...

I saw the solution of the light propagates in cylinder.. so in every solution there is the first order Gaussain function (the slandered one) times another function which gives I think the separation, both of them gives the intensity separation.. So what does that mean?! is it as I draw on the...

Just an idea came up to my mind, I need the equations to know the evanescent field above the waveguide... do you think it is possible to fit a function like "sinc" or similar to obtain filed on the surface? if yes how one can do it

Let's say I have three modes in a fiber that is elliptical cylinder shaped (cylinder with elliptical facet), as in the image below (the source:Optical Engineering, 46(4), 045003 (2007)) so what is the equations that describe these fields..

I read articles talk about the absorption of the exciton in a solvent, such as TIPS Pentracene in toluene. My question is does the absorption spectrum keep the same for aggregate TIPS Pentracene , in case if I want to know for a layer of TIPS Pentracene?! My second question is: let's say I know...

I don't know if that helps you but I just googled Beest–Kramer–van Santen and gave me this results that some articles talk about it: https://www.google.com/search?client=firefox-b-d&q=Beest%E2%80%93Kramer%E2%80%93van+Santen

Image (a) is a view from above of a fused silica sample, the groove depth about one micrometer and the width is about 5 micrometer, the image (b) is a side view of the facet, when I cast a solution with molecules the aggregation is more on the grooves area which is logic, but when I shine a...

Thank a lot you for the answer :)

Thank you so much for your answers :)

I used magnifying glass onto a paper it was so thin :P. It seems my question was not close to what I meant 🙈🙉🙊, anyway can you guess what will happen inside the bulk then?

I know what ablation is, but maybe I didn't explain myself well..., Why should nothing really occur when the focus inside the bulk (material) far from the surface?

Thank you so much for your comment, I think it is more on technique but maybe it is related more to fused silica because I use fused silica... the question is why when the focal point of the laser is under the surface the ablation doesn't occur? (Actually when it is much below the surface and...

I read in couple of articles, like this one: https://link.springer.com/content/pdf/10.1007/BF00324203.pdf that regions of fused silica surface can be ablated by laser... I have two questions: 1- Why does the ablation occur? 2- does the ablation happens when the laser waist point is under the...

Thank you so much for your answer! :) It gives me the way to think about it, really thank you! I just have couple of questions more, do you think if the groove was like a bump so it will be different? and how the roughness of the surface can change the wetting?

View from above of fused silica chip. In the image is fused silica and the black line is burned fused silica caused by laser, when I cast droplet that contains molecules, never mind which kind of aggregation I tried different kinds of molecules, the aggregation is more preferably on the burned...

What is related to the angular momentum is the torque (force), the torque will keep you balanced on the track... let's say you slow down with your bike until zero of velocity so the torque will decrease and then the bike fall down. The concept of ABS is not exactly what you mentioned but to...

Your answer has a lot of sense... actually I can agree with it.. I explained it quite different: positive sign because the force is increasing in the same direction of increasing the displacement toward the source. The linearity is valid for short distances. For long distance displacement if we...

Yes this is the question... in the first article they mentioned that it is F=kx, and in the second article they mentioned F=-kx. and thus the potential will have different sign in every case... which is not compatible! I can agree more with the form F=kx as long as incearsing the distance to the...

In this article https://www.ncbi.nlm.nih.gov/pubmed/30417030 they wrote the gradient force as: F=kx and in this one https://www.nature.com/articles/s41598-018-28876-y they mentioned that U=0.5kx^2 and F=-kx (Which I can't see reason to the minus)... By the way it is not the only articles..

I read in some articles that the force in optical tweezers can be written as: F=kx, with no minus because the force will increase as the distance increased and the particle moves to the source..., This I can understand, but what I can not understand if I make integral (it is conservative force)...

Thank you so much for your detailed answer and the article you shared thank you :) About the three modes alignment, I think as I read in one article it can be both... along the long axis of the ellipse and also along the short axis... it depends on the V-number value... I don't know actually the...

If I have three modes in an optical fiber with elliptical facet as shown in the figure, what would be the polarization direction of the modes... what I know that it is linear polarization and could have several configuration.. but what I want really to know that if could be a situation where the...

I'm really very grateful to you... thank you so much! I have now the way to think about it... thank you :) for now I don't have questions..

Thank so much for your help! :) I have two questions: The first equation I can seek from Snell's law, but why to square them? The second question is why then the mode field tail in sapphire can reach several micrometers but the evanescent field in low medium like gas just few nanometers (it's...

If we look to the figure, in several articles they mentioned that the part of the mode field, the tail of the mode field diameter, travel in the cladding, this maybe I can understand that because of a little change between the refractive indices of the core and the cladding, then the transverse...

Thank you so much for the answers. So what decide the intensity shape? And the second question can I say that the polarization vector of the electric field is shorter and shorter in the sides?

The equation above (from Wikipedia), assumed that the Gaussain beam has polarization in x-direction, as I know that the polarization means that the oscillation direction of the electric field and so the intenisty... so how we get circular intensity in every direction which means in x and y...

Thank you so much man.. the articles are so useful..one of the articles I think it's so close to my case! we''ll see..

The particles has close absorption resonance at the light coupled in the waveguide... and if we say that a gaussian beam propagates in the fiber so anyway there is a gradient force in and out the plane (because the gaussian beam is decaying... So the question is does these two thing causes to...

The point that I have to use a waveguide made in special way with specefic refractive indices as mentioned above. I casted a droplet of toluene contains molecules..., then I got aggregation above the waveguide... I thought it is because gradient force caused by evanescent field... but...

Thank you so much Paul Colby for your answers, it really gave me direction in thinking.. I'm just now looking how would the mode field changed in region where I cast Toluene..

Yes exactly to trap particles... So they will not feel gradient force...?! by the way how would the mode field get changed in this case?!

Let's say the cladding is so thin and the evanescent field is bit large comparing to the cladding, that a portion of evanescent field will reach the droplet..., can you please explain the point about transmission loss...

Let's say that on the surface of the cladding we have evanescent field due to the total internal reflection between the core and the cladding. The refractive indices of the the core is 1.45 and the refractive index of the cladding is 1.4, and I want to use the gradient force of the evanescent...

That's really great it's exactly solved my problem, Thank you sooo much :)