Complex term in refractive index , in context to rayleigh scattering

[royalbird]

I was studying Rayleigh Scattering.

The theory says that Rayleigh Scattering is approximated to x<<1 where x=(2*pi*r)/lambda
where r is the radius of the particle scattering light and
lambda is relative scattering wavelength of light.

lambda = wavelength of light / refractive index of the medium surrounding the particle

my first question is , can the medium be made up of different particles ,like nitrogen,oxygen??

After this the theory states that
m = n - ik
where m = refractive index of the particle
In this notation, n indicates the refraction of light (i.e. n equals the speed of light in vacuum divided by the speed of light in the material), while the complex term is related to absorption.

and absorptivity constant = (4*pi*k)/wavelength of light ,here k is same as above k

my second question is ,what is this absorptivity constant and how to determine it experimentally so as to find k. I need to determine the value of k experimentally.

 

[Jano L.]

my first question is , can the medium be made up of different particles ,like nitrogen,oxygen??

Of course, the air is such a mixture. One then can introduce effective index of refraction of such gas mixture.

and absorptivity constant = (4*pi*k)/wavelength of light ,here k is same as above k

my second question is ,what is this absorptivity constant and how to determine it experimentally so as to find k. I need to determine the value of k experimentally.

Probably it could be inferred from the measurement of light transmitted and scattered by the particles in the gas. But that can be too difficult ands inaccurate. I think easier way would be to find a block of material same as the material that form the particles, measure extinction in it and use electromagnetic theory of Lambert-Beer law to find the absorption coefficient.