I synthesized silver nanowires(AgNW) with diameter of ~ 100 nm, length of 10~50 um. I just want to know whether they can scatter or reflect electromagnetic wave, effectively.
The target frequency of electromagnetic wave is 3~7 GHz. Because wavelength = speed (light) / frequency, 3~7 GHz corresponds to wavelength of 4.3~10 cm. To my best knowledge, if the particle size is much smaller than the wavelength of incident wave, Rayleigh scattering occurs. But, I can't imagine that the electromagnetic wave with a wavelength of a few cm can scattered by very small nanowires. Also, I can't imagine the reflection by nanowires. There is significant difference in dimensions. (cm vs um) I'm not familiar with Optics or Electrodynamics. Please help me understand the phenomenon.
All these phenomena depend on the dielectric constant of the material. In your experiment the Ag NW dielectric constant will not differ from the bulk material (Ag). So I recommend you to look out in a handbook or in anywhere the dielectric constant for Ag. Then using electromagnetic theory you will know certainly how the nanostructure interacts with light (of that energy). However I believe that most of the light will be absorbed. These works are about big nanorods but perhaps will help you.
http://pubs.acs.org/doi/abs/10.1021/jp7120142
http://pubs.acs.org/doi/abs/10.1021/jp075880j
Dear Sung,
Luis is right, however, what about the refractive indices of nanowire? Please do consider because the scattering depends on refractive index of the material.
Please have a look in to the following papers:
http://onlinelibrary.wiley.com/doi/10.1111/php.12205/full
http://pubs.rsc.org/en/content/articlehtml/2014/cc/c4cc02750g
http://www.sciencedirect.com/science/article/pii/S0167577X15000282
http://pubs.acs.org/doi/abs/10.1021/nl500838q
http://nanophotonics.spiedigitallibrary.org/article.aspx?articleid=1812974
Dear OP, I would say that your intuition is not so bad but also that the previous posters gave good advice.
3-7 GHz is a small frequency compared to the plasmon frequency in silver. So you can consider what happen in purely classical terms, and governed by both, real and imaginary part of the dielectric function (of both, rod and surrounding).
Scattering may be weak under these circumstances (ratio between wavelength and characteristic dimension) but will be nonzero. Think of the incoming wave finding the rod. The rod does introduce new boundary conditions to the electromagnetic field at its surface. Therefore, the solution to the problems with and without the rod will differ both inside and outside the rod. You will get energy dissipation in the rod and some scattering intensity outside. The amplitude of the scattered waves may be (very) low, though.
Scattering is certainly the more appropriate term compared to reflectivity. But reflectivity may also be thought of the coherent superposition of scattering from a dense planar distribution of scattering sites (i.e. a surface).
Dear Collegues, Thank you for your replies. I should like to do intensive study in this field. Now I guess energy dissipation (absorption) due to dielectric loss triggered by Ag nanowire is much more dominant than scattering or reflection. I'm preparing freestanding reduced graphene oxide (RGO)/Ag nanowire hybrid films for electromagnetic (EM) wave shielding. The addition of Ag nanowire enhances both reflection and absorption of EM wave. I must take a look at dielectric properties of AgNW. Thanks again!
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