Development and application of a low-cost vaporizer for rapid, quantitative, in situ addition of organic gases and particles to an environmental chamber

Environmental chamber studies are widely employed to investigate atmospheric chemistry and aerosol formation. However, the large surface area-to-volume ratio of a chamber leads to effects that need to be accounted for in order to apply the results of chamber studies to the ambient atmosphere. These include, but are not limited to, gas-wall partitioning and particle deposition to walls, both of which can impact quantification of reaction products. Here, a low-cost vaporizer was developed to provide a means to rapidly create well-characterized organic vapors and aerosol particles inside the chamber. This in situ approach eliminates the losses to surfaces that can occur when organic gases or particles are created in a device outside the chamber and then transported inside through tubing, thus providing a simple means for achieving quantitative addition. Thermally stable volatile organic compounds can be added to the chamber within similar to 1 min, which allows for accurate measurements of gas-wall partitioning timescales and equilibrium using gas chromatography. The vaporizer can also be used to create low-volatility organic aerosol particles with a mean diameter of similar to 150 nm and selectable mass concentration as low as 5 mu g m(-3)via homogeneous nucleation within a few minutes. Such an aerosol can be used to calibrate or evaluate the performance of instruments such as the scanning mobility particle sizer in laboratory and field studies. Copyright (c) 2020 American Association for Aerosol Research