The Correlator

The NanoBrook instrument relies on the instrument control software known as Particle Solutions as well as its high-speed processing hardware, and more specifically, the TurboCorr correlator. The correlator processes real time DLS data and sends the information to Particle Solutions for fitting, which is displayed in the form of an autocorrelation function.

The Autocorrelation Function

The autocorrelation function (ACF) is a mathematical tool used to assess the self-similarity of a signal, C(T) with a time-shifted version of itself T µs. An example of an ACF can be seen in the figure below. In Dynamic Light Scattering (DLS), the ACF quantifies the rapid intensity fluctuations caused by the Brownian motion of particles in suspension. By analyzing changes in the intensity of scattered laser light, the ACF generates particle size distributions. This transformation of raw DLS data enables the calculation of the effective diameter and polydispersity index (PDI) through Cumulants analysis. For more detailed size distributions, advanced regression methods like Non-Negative Least Squares (NNLS or CONTIN) are applied to produce multimodal size distributions (MSDs).

Particle Solutions v4 – The New Customizable Correlator Layout

Particle Solutions v4 introduces the new feature of a customizable correlator layout, which allows for more in-depth analysis of a sample. Additionally, the new customizable correlator allows for the testing of samples with higher viscosities, lower temperatures, or low mobilities. The components of the new correlator layout that can be customized include the first delay, the last delay, and the channels, whereas in the previous versions of Particle Solutions, these components were fixed and unmodifiable.

Case Studies

To help create a better understanding of the new customizable correlator layout, several case studies were conducted to examine the effects of changing the first delay, last delay, or channels in the customizable correlator layout, on different samples.

In Part 1: The New Customizable Correlator Layout – First Delay, a 20 nm polystyrene latex (PSL) standard diluted in 10 mM KNO₃ was tested using three different first delay settings including 2 µs, 1 µs, and 0.100 µs.

In Part 2: The New Customizable Correlator Layout – Last Delay, an 88 nm PSL monodispersed standard diluted in 10 mM KNO₃ was tested at two different last delays including 1.0×10³ µs and 1.0×10⁶ µs.

Finally, in Part 3: The New Customizable Correlator Layout – Channels, a sample containing both 88 nm and 600 nm PSL standards diluted in 10 mM KNO₃ was tested using the following channels: 20, 50, 150, 200, 250, 316.

Understanding the new customizable correlator layout features will help the user recognize the capabilities of the correlator layout and how to establish settings that are best suited to one’s sample.

Downloads

Part 1: The New Customizable Correlator Layout – First Delay
Part 2: The New Customizable Correlator Layout – Last Delay
Part 3: The New Customizable Correlator Layout – Channels

If you require more information or have any questions, please contact our team directly.