Rayleigh form factor sphere

In summary, the diflBculties in determining aggregate form factors, particle form factors, phase shifts, and distribution functions combine to make the Rayleigh-Debye approach too complicated for practical application. On the other hand, the coalesced-sphere approach using the Jobst approximations to the Mie scattering eflBciencies allows rapid correlation of turbidity with particle size distributions. Consequently, a coalesced-sphere approach was adopted for experimentation in the E. coli-PEI system. 

The factor occurs in the definition of the Rayleigh ratio because the hght wave spreads out over a sphere of radius r and surface area 4ltr so any sample of the radiation has its intensity 7(6) decreased by a factor proportional to Therefore, the quantity 1(6) X r, and not simply 7(6), should be compared to Ig in forming the Rayleigh ratio. 

---