The peak particle size and expanded uncertainties (95 % confidence interval) for two new particle calibration standards are measured as 101.60 nm ? 1.02 nm and 60.68 nm ? 0.59 nm. The particle samples are polystyrene spheres suspended in filtered, deionized water at a mass fraction of about 0.5 %. The size distribution measurements are made using a differential mobility analyzer (DMA) system of aerosolized particles. An electrospray aerosol generator was used for generating the 60 nm aerosol to minimize the generation of multiply charged dimers and trimers and to minimize the effect of non-volatile contaminants increasing the particle size as an aerosol. The testing for the homogeneity of the samples and for the presence of multimers using dynamic light scattering is described. The use of the transfer function integral in the calibration of the DMA is discussed and comparison is made with the previously used calibration approach. A significant consideration in the uncertainty analysis was the correlation between the slip correction of the calibration particle and the measured particle. Including the correlation reduced the expanded uncertainty from approximately 1.9 % of the particle size to about 1.0 %. The full size distributions for both the 60 nm and 100 nm spheres are tabulated and selected mean sizes including the number mean diameter and the ZAVG diameter are computed. The use of these particles for calibrating DMAs and for making deposition standards for surface scanning inspection systems is discussed.
Citation: Journal of Research (NIST JRES) -
Volume: 111 No. 4
NIST Pub Series: Journal of Research (NIST JRES)
Pub Type: NIST Pubs
differential mobility analysis, dynamic light scattering, electrical mobility, electrospray aerosol generation, particle size calibration standards, transfer function