Classes ended a month ago and now we have warm days and a more relaxed schedule. This doesn’t mean things have slowed down, however. Two papers from the group were recently accepted for publication in an upcoming special issue of Aerosol Science and Technology that will honor Pete McMurry. For those of you who don’t know Pete, he’s an extraordinary aerosol scientist and bicyclist who recently retired from full-time professoring … but not from biking as evident by this pic of his Oregon – Minnesota tour last summer:

Pete taking a break in Montana during his Portland – Minneapolis tour.

The following two papers were accepted for publication:

“Water-Condensation Based Nano-Particle Charging System: Physical and Chemical Characterization,” Nathan Kreisberg, Steven Spielman, Susanne Hering, Danielle C. Draper, Michael J. Lawler, and James N. Smith, Aerosol Science and Technology, in press. This paper describes a water-condensation based system that we developed with Aerosol Dynamics, Inc., to enhance both the charging efficiency and the concentration of sub-20 nm particles for TDCIMS. We call the instrument “Stanley” because it’s made entirely out of stainless steel. Experiments with TDCIMS shows minor contamination of sampled nanoparticles as a result of this charging mechanism.

“Size Resolved Chemical Composition of Nanoparticles from Reactions of Sulfuric Acid with Ammonia and Dimethylamine,” Haihan Chen, Sabrina Chee, Michael J. Lawler, Kelley C. Barsanti, Bryan M. Wong, and James N. Smith, Aerosol Science and Technology, in press. This paper investigates nanoparticle formation and growth driven by acid-base chemistry from sulfuric acid (H2SO4) with ammonia (NH3) or dimethylamine (DMA). In these experiments with a flow tube we observed that the smallest (sub-10 nm diameter) particles were more acidic than bulk thermodynamics predicts, but that as particles grow to ~30 nm they become less acid. Modeling performed by our colleagues at UC Riverside show that, as particles decrease in size, the acids become “less acidic” and bases become “less basic.” We are still exploring the exact reasons for this behavior.

Once we finalize the corrected manuscripts we will make them available for download on our website.