I’m reminded of de-sodium-fusion but will avoid this as an opening sentence as it will be understood by but a few chemists……  Ah well, wrong again….

In England, in the early 1800’s, there was a group formed solely for the ‘diffusion of knowledge’.  It was actually more correctly called “The Society for the Diffusion of Useful Knowledge (SDUK) founded in 1826, and wound up in 1848.  The Society published inexpensive texts intended to adapt scientific material for the rapidly expanding reading public. Wikipedia further states “An American group of the same name was founded as part of the Lyceum movement in the United States around the same period. Its Boston branch sponsored lectures by such speakers as Ralph Waldo Emerson, and was active from 1829 to 1947.  Henry David Thoreau cites the Society in his essay “Walking,” in which he jestingly proposes a Society for the Diffusion of Useful Ignorance”.

We also have to make our instrumentation and software easy to use rather like the SDUK.  We need to diffuse our years of expertise and knowledge into our instruments knowing that they will be used by anyone despite their background. Education and training and our applications support is one area where Malvern Instruments makes a big difference in relation to the other vendors out there.

If you look at a number of our technologies you’ll see the importance of diffusion at the most fundamental level.

Dynamic Light Scattering (DLS) – Zetasizer Nano ZS

The Stoke-Einstein equation is used to obtain a hydrodynamic diameter (dH) or radius (rH) from a calculated diffusion coefficient (D):

Equation AR blog Feb2016

where K is Boltzmann’s constant, T is the absolute temperature and h is the viscosity of the medium that the particle travels in.  The size derived here is based on an ensemble technique and provides an intensity-based mean value.  Yes, a simple equation easily understood – the higher the temperature or the lower the viscosity then the quicker the movement or diffusion.

Nanoparticle Tracking Analysis (NTA) – Nanosight

Actually more information than just nano, ISO is referring to this technique as Particle Tracking Analysis (PTA)…… This relies on direct measurement (as opposed to calculation) of the diffusion coefficient.  It uses the same Stoke-Einstein equation that we stated above for measurement of particle size distribution on a number basis.

Taylor DispersionViscosizer TD

This doesn’t refer to graffiti on a wall, although it could…..



Here we have:


Where the molecular diffusion coefficient (D) is inversely proportional to peak width (σt) at the detection window Rc is the capillary radius and t0 is the residence time.  For small molecules, D is large and the width of the resultant Taylorgram is relatively small. For large molecules, D is small and the width of the resultant Taylorgram is larger.

Here we see an equation for molecular diffusion where we had particle diffusion previously.

How do we diffuse all these scientific knowledge in our technology arsenal?   A wide variety of routes exist – through the webinar program for one – as well as applications notes and one-on-one training.

Last year, I looked at other aspects of diffusion including Graham’s Law and Fick’s Law taking in a bunch of important scientific personalities.  Check it out: The importance of the measurement of diffusion in 2-phase systems

Here’s DLS, NTS, and Viscosizer TD webinars on the specific topics designed to educate you. Why not look at the wonderful search feature on our web site?

DLS research

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