Measurement of the 100 nm NIST SRM 1963 by Differential Mobility Analysis

The number mean diameter of 100 nm NIST Standard Reference Material (SRM) 1963 was measured to be 100.7 nm with an expanded uncertainty at the 95% confidence level of 1.0 nm by measurement with the differential mobility analyzer (DMA). The low level of uncertainty resulted from the use of the 1.0 μm SRM 1690 for calibrating the DMA. The largest single component of the Type B (systematic) uncertainty was a 0.29 nm uncertainty in the calibration diameter. Measurements of the 0.3 μm SRM with the calibrated DMA give results within 0.001 μm of the certified diameter. Results obtained by other investigators using transmission electron microscopy (TEM), angle dependent light scattering, electro-gravitational aerosol balance, and atomic force microscopy are consistent with this DMA value. The 100 nm NIST SRM 1963 and the Japanese 100 nm Calibration Standard are shown to differ by 10% based on TEM analysis and DMA measurements. This size difference has a significant effect on the calibration of scanning surface inspection systems and optical particle counters.