Re-evaluation of the slip correction parameter of certified PSL spheres using a nanometer differential mobility analyzer (NDMA)

The slip correction parameter measured by Kim et al. (2005) is re-evaluated with the newly issued current smallest standard reference material SRM® 1964 (PSL 60.39 nm). The same experimental method utilizing the electrical mobility technique under low pressure condition is used. From the measured peak voltages at low pressures down to 8.63 kPa (Kn=81), slip correction factor (C) is calculated, and then the slip correction parameter (A) is obtained by nonlinear curve fitting. The parameter A is 1.165 + 0.480 exp ( − 1.001 / K n ) with the asymptotic value of 1.645 for the free molecular regime, which corresponds to a diffuse reflection fraction of 0.873. The value of A is at most 0.1% different from the value reported by Kim et al. (2005) 1.165 + 0.483 exp ( − 0.997 / K n ) and the uncertainty is reduced by about 0.5% to a value of about 1.5%.