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Jim Smith Scientist II Ultrafine Aerosols Group Atmospheric Chemistry Division National Center for Atmsopheric Research jimsmith@ucar.edu (303) 497-1468

Research Interests

I am interested in ultrafine particles in the atmosphere. These are particles with diameters smaller than 100 nm, or about a thousandth the diameter of a human hair. Although these particles are very small, they can have huge effects to our health and climate:

• They can trigger severe respiratory problems because they are inhaled deeply into the lungs. The smallest particles even have the ability to pass through cell membranes and thus move from the lung tissue to just about every organ in the body!
• They are also subset of particles upon which cloud droplets form. Understanding their chemical composition will improve our understanding of how clouds form, as well as how human and biogenic activity may influence our climate.

I am an experimentalist, meaning I use both controlled experiments in my laboratory as well as observations in a variety of locales to study ultrafine particle physical and chemical properties. The most important tool that I use is called a Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS).

The TDCIMS was developed in collaboration with Peter McMurry's group at the University of Minnesota. This instrument allows us, for the first time, to measure the chemical composition of particles as small as 4 nm in diameter.

Community Service

Graduate and Postgraduate Education

I have two ASP graduate students in my laboratory. ASP is a program that supports university Ph.D. thesis research projects that are collaboratively guided by a university faculty member and an NCAR scientist.

Name	Host University	Co-advisor	Research Project
Matthew Dunn	University of Colorado	Jose Jimenez	Chemical and physical properties of atmospheric ultrafine particles
Sara Lance	Georgia Institute of Technology	Athanasios Nenes	Understanding the effects of chemical composition on hygroscopicity and cloud condensation nuclei activity

I also work with Tim VanReken, an ASP Postdoctoral Fellow. The ASP postdoctoral program differs from most postdocs in its primary objective, which is to develop the careers of recent Ph.D. graduates. The program encourages independence and creativity while providing an environment in which fellows interact with and receive advice and lab resources from NCAR scientists.

Biosphere/Atmosphere Exchange Facility

In collaboration with Alex Guenther's Biosphere/Atmosphere Interactions Group and my ASP postdoc Tim VanReken, I am developing a Community Biosphere/Atmosphere Exchange Facility. This facility will be located in the collaborative laboratory space in the new Atmospheric Chemistry Division building when we move there in spring 2006.

The two primary components of the facility are a biogenic emissions enclosure and an aerosol reaction chamber. Experiments are initiated by continuously passing clean, dry air over a live branch in the biogenic emissions enclosure. This sample air is fed to the aerosol growth chamber, where it is mixed with clean air containing an oxidant (such as ozone) at approximately ambient concentrations. The reaction between the biogenic compounds and the oxidant is then monitored using various gas- and particle-phase measurement techniques.

We hope that this facility will be a community resource. Additionally, the chamber could also serve as an focal point for workshops and colloquia on a variety of subjects involving atmospheric chemistry and biogeosciences.