PARTICLE-SIZE-MEASURING IN THE NANOMETER-RANGE Addition 1

In my recent blog on this theme I stated:

These early instruments needed a very robust and simple calculation mode, the ‘2nd Cumulant’ method, for evaluation because the calculation power of the then available computers were still very limited. Still today this simplified calculation method is positioned in the related ISO 13321 framework. It generates as results a mean particle diameter and a value for the width of an assumed Gaussian distribution only.

Regarding this rather abreviated definition of the results given by 2nd Cumulant method I was asked to correct it to a precise one.

As 2nd Cumulant is a typical series expansion it is not resulting in any, whatever shaped curve but in a series of moments. As the name indicates only the first and second moment of this series are evaluted. The first moment gives the value for the mean diameter and the second moment gives the width . These two values are the only result of the 2nd Cumulant method. Today nearly all instruments also do graphical reports and only for this they show an assumed Gaussian distribution based on the two values given by the first two moments of the series expansion.

This means that scientifically and mathematically correct the result of a 2nd Cumulant evaluation is only the mean diameter and the width. The presented graph as a Gaussian distribution is correctly not the result but only one possibility to ease understanding to visual skilled creatures as we are.   

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Tags: PCCS, PCS, Zeta, correlation, cross, dynamiclight, measurement, scattering, size

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Publications by A. Paszternák:

Pd/Ni Synergestic Activity for Hydrogen Oxidation Reaction in Alkaline Conditions

The potential use of cellophane test strips for the quick determination of food colours

pH and CO2 Sensing by Curcumin-Coloured Cellophane Test Strip

Polymeric Honeycombs Decorated by Nickel Nanoparticles

Directed Deposition of Nickel Nanoparticles Using Self-Assembled Organic Template,

Organometallic deposition of ultrasmooth nanoscale Ni film,

Zigzag-shaped nickel nanowires via organometallic template-free route

Surface analytical characterization of passive iron surface modified by alkyl-phosphonic acid layers

Atomic Force Microscopy Studies of Alkyl-Phosphonate SAMs on Mica

Amorphous iron formation due to low energy heavy ion implantation in evaporated 57Fe thin films

Surface modification of passive iron by alkylphosphonic acid layers

Formation and structure of alkylphosphonic acid layers on passive iron

Structure of the nonionic surfactant triethoxy monooctylether C8E3 adsorbed at the free water surface, as seen from surface tension measurements and Monte Carlo simulations