LAUSR

Scanning Electron Microscopy (SEM) technique is widely used for characterizing nanoparticle (NP) size but very few papers deal with NP dimensional metrology. This article reports on the methodology to evaluate the uncertainty budget associated with the measurement of the mean diameter of standard silica NP population by SEM. In this context, the effect of potential error sources have been evaluated though a metrological qualification of the instrument. The measuring method, consisting in determining the area equivalent diameter taken at middle height (Deq-FWHM) has been tested on reference silica NP with an indicative certification value given by SEM/TEM (number based modal diameter). Because agglomeration phenomenon can bring measurements errors, semi-automatic homemade software has been used to build the diameter distribution histogram selecting only isolated particles. Finally, the uncertainty budget including main experimental components has been established for the mean diameter measurement of this silica NP population. The main contributors of this uncertainty budget are the resolution linked to the dimension of electron beam diameter at focal plane, the calibration uncertainty on references NP and the measurement repeatability.