Self-Assembly of Synthetic and Biological Polymeric Systems of ...

autocorrelation function (ACF). In the time domain, the correlation function usually decays
with time (Figure 2.8), and faster dynamics leads to faster decorrelation of the scattered
intensity trace. It can be shown that for a random process the intensity ACF is the Fourier
transform of the power spectrum and, therefore, DLS measurements can be equally well-
performed in the spectral domain. In fact, DLS experiments were initially discussed in terms of
the broadening of the spectrum peak of monochromatic light due to Doppler shifts
experienced by propagating light waves scattered by moving particles (31).
Figure 2.8. Illustration of autocorrelation function (31).
To detect the intensity fluctuation with time, a DLS system requires an autocorrelator on top
of a regular SLS system, as shown in Figure 2.9.
Figure 2.9. Sketch of a dynamic light scattering system. The pulse amplifier discriminator
converts the analogic signal of the photodetector, I(t), in a digitalized signal, which is further
processed by the autocorrelator into the autocorrelation function.
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