A complete description of the highly complex scattering behavior involves the application of Mie scattering. The above isotropic assumption holds true for particles that are considerably smaller than the wavelength of the illuminating light, usually 632.8 nm in the Zetasizer Nano. Yet, it is vital to observe that both are simply different representations of the same physical reality of a distribution of various sizes. Practically, this usually means that the intensity distributions highlight the larger particles in the distribution in contrast, the number distributions highlight the smaller particles in the distribution. In the case of real-life distributions, the situation can be modeled in a manner similar to the simplified two-particle model used above as an example. Where %I a is the relative amount of intensity of the particle with size a. Consequently, the relative contribution from a in terms of intensity is Lastly, for small, isotropic particles, the scattering intensity from a spherical particle is equivalent to the size to the sixth power. Where %V a is the relative volume of the particle with size a. Consequently, the relative contribution from a in terms of volume is Supposing that the particles are spherical, the particle volume is equivalent to the size to the third power. Where %N a is the relative number of the particle with size a. If there are N a particles with the size a and N b particles with size b, then in terms of number, their relative contributions compared to the other particle are Are these three distributions different? The answer is yes.Ĭonsider a simple example of a distribution containing only two particles, particle species one with size a and particle species two of size b. The intensity distribution gives the amount of light scattered by the particles in the different size bins. The volume distribution demonstrates the total volume of particles in various size bins. The number distribution demonstrates the number of particles in the various size bins. This type of distribution would precisely be signified as an “age distribution by number.” Three types of distributions are generally encountered when particle size distributions are important. For instance, an age distribution of a group of people might reveal the number of members of that group in every age category. An explanation of the probability of encountering a specific value of a variable is called a distribution. Several things in nature have characteristics that demonstrate variations. In this article, a titanium dioxide sample has been used as an example for highlighting the differences between the three distributions. So which one must be selected? Comparing stated dimensions from one technique with those from another can be complicated and should be employed with caution: distributions in terms of number, volume, or scattering intensity usually produce extremely varying results - in spite of expressing precisely the same physical characteristics of a sample. However, the particle size can be obtained by several techniques. Sponsored by Micromeritics Instrument Corporation Sep 17 2018Īn important parameter of colloidal systems is their particle size.
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