AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Characterization of Aerosols Using an Electrodynamic Linear Quadrupole Trap
MATTHEW HART, Erin Davis, Jason Edmonds, Jay Eversole, Naval Research Laboratory
Abstract Number: 341 Working Group: Bioaerosols: Characterization and Environmental Impact
Abstract The physical characteristics of single, micron-sized particles are studied as they are confined along the axis of an electrodynamic quadrupole trap (ELQ) . Using an ELQ, single to several hundreds of particles simultaneously, can be studied in an atmospheric controlled, touch-less environment. The ELQ design is similar to both earlier 3-dimensional ring versions and linear ion traps used for mass spectrometry. One of the advantages of this approach over the ring version is its relative ease, or increased efficiency, of particle capture. The electrodynamic stability region of the ELQ is along the symmetry axis defined within four parallel, equally spaced rods where charged, micron-sized particles can be captured and confined at ambient atmospheric pressures. Captured particles can be transported along the axis using a controlled airflow along the length of the device or held stationary by applying an electric potential to a concentric ring that has the same polarity of the trapped particles creating a balance against the airflow and/or gravity. This trapping technique permits the study of particles over long time periods so that they may be subjected to challenging conditions of interest such as temperature, relative humidity, gas composition and EM radiation. Diagnostic measurements, such as particle size, can be obtained at points along the length of the ELQ using imaging and light scattering techniques. Particles may also be collected for additional diagnostic measurement outside the ELQ by depositing them onto a substrate through the end of the chamber controlled by the ring potential. Exploiting this collection capability, viability studies of aerosolized biological organisms are targeted for future study. As an initial example of the utility of this approach, we present data on evaporation rates of liquid droplets for specific neat materials and binary mixtures, and compare these data to predictive models using known bulk properties.