Theoretical Investigations on the Light Scattering of Spheres. XIV. Wavelength Exponent of Differential Scattering Spectra for an Angle of Observation of 90°

Exact equations are given for the wavelength exponent of experimental differential scattering spectra (n₉₀)₀ observed at an angle of 90° with respect to an incident unpolarized beam. Numerical values of the theoretical exponent n₉₀ are derived from the Mie functions for α=0.5 (0.1) 0.8 (0.2) 6.4 and m=1.05 (0.05) 1.30. Values of the quantity $\mathrm{[\partial }\ln {\mathrm{(I}}_{90}{\mathrm{/I}}_o\mathrm{c)/\partial m]}$ are also computed for α=0.8 (0.4) 2.4 and the above m values. Advantages and disadvantages of a practical application of (n₉₀)₀ for particle size determination are enumerated.