High order Tyndall spectra HOTS

When a dilute suspension of sufficiently large, mono-disperse, spherical particles is irradiated with white light, vivid colors appear at various angles to the incident beam. The angular positions of the spectra depend on m and D, hence they may be used to determine particle size in colloidal suspensions. 

HOTS have been studied extensively in monodisperse sulfur solutions by La Mer et.al. [98-101], by Kenyon [102], in aerosols by Sinclair and La Mer [103], in polystyrene latices by La Mer and Plessner [105] and in butadiene latices by Maron and Elder [106]. The following equations derived by Maron and Elder for the angular positions of the first red and green order, and are particular examples of equation (10.22). 

Pierce and Maron [107] show that the angular positions of the red orders are identical with the angles at which minima occur in the intensity of the scattered light when the incident light has a wavelength of 2. Similarly, 

The above equations yield weight average diameters. m the evaluation of D becomes more difficult due to intensity of the maximum and broadening of the peak, been used for the size range 0.26 to 1.01 pm [108]. 

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For Rayleigh scattering / = 0 at 90°. As R increases, theory shows that X is a periodic function of diameter for monosize particles, and this has been used to measure particle size [78] specifically the size of aerosols in the size range 0.1 to 0.4 pm [79]. It has also been used to determine the sizes of sulfur solutions [80] In this work, transmission and polarization methods yielded results in accord with high order Tyndall spectra (HOTS) for sizes in the range 0.365 to 0.62 pm. In the limited region where (0.45[Pg.537]

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