# Complex term in refractive index , in context to rayleigh scattering

1. Jun 28, 2012

### 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.

2. Jun 28, 2012

### Jano L.

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

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.

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