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.