Tyndall vs Rayleight Light Scattering

[inigo]

I've been trying to get some insight into the light scattering mechanism that occurs in colloidal solutions via the Tyndall effect and was hoping some of the resident experts here could shed some light... on this.
Tyndall scattering occurs with particles that are roughly the size of the wavelength of light while Rayleigh scattering occurs with very small particles (< 1nm) such as O2 and N2 in the atmosphere. The Rayleigh scattering mechanism is when energy from the light wave excites the O2 or N2 electrons to a higher unstable state. When the electron returns to its lower stable state, a photon of the same frequency is released in a random direction. My question is, does this same process also happen with larger particles via Tyndall scattering or is it more like a random refraction where the light wave is simply redirected on a complex path through the particle? Blue light gets scattered more via the Rayleigh effect because it has more energy to excite the electron to a higher unstable state but does blue scatter more via the Tyndall effect due to a higher degree of refraction just due to its shorter wavelength?
Thanks!

 

[DrDu]

Although Tyndall effect is well known, the scattering from particles about as large or larger than the wavelength of light is called Mie scattering, not Tyndall scattering. The transition from Rayleigh to Mie scattering is continuous. The original paper by Mie contains all you ever want to know about it.

Your description of the Rayleigh scattering doesn't sound right to me: The molecules never get excited to an unstable state, at least not in the visible range of the spectrum, which would be a resonant scattering event.

 

[inigo]

I see that Mie scattering is the more general solution to light scattering. I'm not positive on the root mechanism for Rayleigh/Mie scattering. I got the excited electron state for Rayleigh scattering from this site: http://library.thinkquest.org/27356/p_scattering.htm Could be incorrect as applied to Raleigh scattering. I am looking at the Tyndall effect as it applies to colloidal solutions (gelatin mixed in water) and I am trying to understand the limitations of modeling the Rayleigh effect via measuring the Tyndall effect. It's easy to setup an experiment to measure the Tyndall effect in a colloidal solution vs trying to measure O2 N2 scattering in large volumes of air. Makes me wonder how Lord Rayleigh did it?

Thanks,