Slip Correction Measurements of Certified PSL Nanoparticles Using a Nanometer Differential Mobility Analyzer (Nano-DMA) for Knudsen Number From 0.5 to 83.
Slip Correction Measurements of Certified PSL
Nanoparticles Using a Nanometer Differential Mobility
Analyzer (Nano-DMA) for Knudsen Number From 0.5 to 83.
Kim, J. H.; Mulholland, G. W.; Kukuck, S. R.; Pui, D. Y.
Journal of Research of the National Institute of
Standards and Technology, Vol. 110, No. 1, 31-54,
nanoparticles; electrospray; Knudsen number; polystyrene
latex particles; slip correction factor
The slip correction factor has been investigated at
reduced pressures and high Knudsen number using
polystyrene latex (PSL) particles. Nano-differential
mobility analyzers (NDMA) were used in determining the
slip correction factor by measuring the electrical
mobility of 100.7 nm, 269 nm, and 19.90 nm particles as
a function of pressure. The aerosol was generated via
electrospray to avoid multiplets for the 19.90 nm
particles and to reduce the contaminant residue on the
particle surface. System pressure was varied down to
8.27 kPa, enabling slip correction measurements for
Knudsen numbers as large as 83. A condensation particle
counter was modified for low pressure application. The
slip correction factor obtained for the three particle
sizes is fitted well by the equation: C = 1 + Kn ( a + B
exp(-y/Kn)), with a = 1.165, B= 0.483, and y = 0.997.
The first quantitative uncertainty analysis for slip
correction measurements was carried out. The expanded
relative uncertainty (95% confidence interval) in
measuring slip correction factor was about 2% for the
100.7 nm SRM particles, about 3 % for the 19.90 nm PSL
particles, and about 2.5% for the 269 nm SRM particles.
The major sources of uncertainty are the diameter of
particles, the geometric constant associated with NDMA,
and the voltage.