| Popis: |
Traceability of the transmission electron microscopic (TEM) method for the determination of the diameter of polystyrene latex (PSL) particles was established by calibrating the internal length standard by a method traceable to the international length standard, the wavelength of the iodine stabilized helium–neon laser system. The TEM method uses a diffraction grating replica as internal length standard to compensate the magnification of the TEM (Katsuta et al., 6th Symposium on Aerosol Science and Technology, 1988, p. 64; Katsuta et al., J. Aerosol Res. 2 (2) (1987) 134). Shrinkage of the PSL particles by the electron beam was also compensated for by extrapolating the shrinkage to time zero. Diameters of National Institute of Standards and Technology (NIST) standard reference material (SRM) PSL particles were measured according to the TEM method, and differences between the average diameters of NIST and those of the TEM method were as large as a few nanometres for both nominal 0.3 μm (SRM #1691) and 1 μm (SRM #1690) NIST SRMs. The particle number concentrations were determined by direct observation with a scanning electron microscope (SEM) of a PSL suspension on a silicone wafer. |
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