Hello dear researchers, Hope so you all will be fine and doing great research.I want to ask the following questions about the internal field of nano-particles:
1) we can calculate the field by wave optics discussing the max-wells equation and we also can calculate the field by quantum mechanics. which method is best in your point view and why?
2) what are the differences in the optical field map inside the nano-particle for the given shape,wavelength and size of metallic, dielectric and semiconductor nano-particle??
3) what are the basic difference in internal field field map making and why?
Please share your thoughts or suggest really a useful literature. Thanks in advance
Since you are dealing with nanoparticles, quantum aspects must be taken into account. In any decent book on quantum mechanics you can find a couple of chapters on electrodynamics which is studied with a quantum mechanics approach. And if the particle are moving at relativistic speed, then you have to approach the problem with QED (quantum electrodynamics) approach.
Hi Kaleem
Before answering your question properly, I need some more information. In particular, which kind of particle do you have in mind, in term of composition and size and what do you want to do with these nanoparticles. Anyway, going for a brief answer:
best
http://onlinelibrary.wiley.com/book/10.1002/9783527618156
@Giovanni Pellegrini thanks for your's reply. The particle size is of about 1 microns, the shape is 94% spherical, I have used Polarization microscopy, the crystal system of the particle is cubic, and it is a semiconductor particle, I used 532 wavelength light.
Are you above or below the band gap in terms of energy of the incident light? This changes everything. Below bandgap your particles is a dielectric and is perfectly transparent. Above bandgap is a completely different story. Anyway, once the optical constant of the semiconductor is known (what semiconductor are you using?) a simple calculation with Mie theory will provide you with the internal field distribution of your particle, since we are dealing with an almost spherical shape.
The incident light energy is above band-gap. except experimental results, i have calculated field by using three methods FDTD, FEM and Mie . For some parameter calculations the result much closer to experimental result but for some it is a little closer. about internal field my FEM calculations are much closer to the experimental results more than Mie. but i did not understand why some pattern of field inside the the particle is different, almost in every particle field make quadrupole.
Thanks Sudarson for your reply, I have done 3D calculations. yes i know its hard that is why i have asked in my question which method can be suitable should we include quantum effects for example if the particle is of one micron then can we get each atom response to the light inside the particle and integrate? and form image to show the pattern of light???
Yes, I know that is why I am asking. What you mean by Only quantum mechanical sum may give you wrong number depending on your system?? can you explain it?
Hi kaleem
Elaborating on my answer and on your calculations:
Best
@Giovanni Pellegrini, Thanks for your's reply, can I know distribution inside the particle just finding absorption spectra of the particle?? I want to confirm the experimental results. I have performed imaging measurement with my system and with conventional OPtical Olympus microscopy. My system give quadrupole inside the particle i.e one positive lobe and one negative lope whereas conventional did not give me mapping of internal field.
- Spectra are useful to compare theoretical results and to understand the nature of modes
- What's the meaning of one positive lobe and one negative lobe? Intensity, Phase? I do not understand
- Usually two lobes indicate dipoles and not quadruples
- Again, if you do not provide some context, this discussion is not going to end anywhere
Best
Hello, Giovanni, The imaging system to whom I am talking about can be analyzed from the following paper:
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-22-17-20446
In the spectra which I calculated from Mie, FDTD and FEM have shown like this as shown by figure but experimentally it also make dipole inside not just in near field but from the theory and simulations it comes to knowledge that the dipole does not clearly appear inside the particle why??? I have also tried to change the intensity map but in vain: so should I do need to change some of the parameters of my simulations???
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