| US 7,516,019 B2 | ||
| Method for online measurement of ultrafine aggregate surface area and volume distributions | ||
| Sheldon K. Friedlander, Los Angeles, Calif. (US); and Anshuman A. Lall, Los Angeles, Calif. (US) | ||
| Assigned to The Regents of the University of California, Oakland, Calif. (US) | ||
| Filed on Jul. 28, 2006, as Appl. No. 11/495,154. | ||
| Claims priority of provisional application 60/703728, filed on Jul. 29, 2005. | ||
| Prior Publication US 2007/0043520 A1, Feb. 22, 2007 | ||
| Int. Cl. G01N 31/00 (2006.01) | ||
| U.S. Cl. 702—29 [422/151; 428/403] | 20 Claims |
| 1. A method of estimating the number of nanoparticle aerosol aggregates having a primary particle size a in a gas using a
differential mobility analyzer for measuring spherical particles, comprising:
a) passing a volume of a gas containing entrained nanoparticle aerosol aggregates through the differential mobility analyzer
for measuring spherical particles;
b) obtaining the primary particle size a of the aggregates;
c) obtaining a mobility diameter dm of the aggregates;
d) counting a total number of aggregates nsph that pass through the differential mobility analyzer;
e) equating a migration velocity of an aggregate to that of a spherical particle having the same mobility diameter dm to obtain a number N of primary particles in the aggregate particle;
f) determining a fraction of aggregates ηagg that are singly electrically charged by the differential mobility analyzer; and
g) estimating the number of aggregates nagg in the volume of gas from the counted total number of aggregates nsph and the charge fraction ηagg.
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