AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Performance of a New Tandem Differential Mobility Analyzer Inversion Routine to Interpret Non-Ideal Responses
CHRISTOPHER OXFORD, Brent Williams, Washington University in St. Louis
Abstract Number: 510 Working Group: Instrumentation and Methods
Abstract Non-ideal (multi-modal and asymmetric) response curves from a Tandem Differential Mobility Analyzer (TDMA) can occur while evaporating aerosols during volatility experiments or while condensing water on aerosols in an unstable relative humidity environment. TDMA inversion routines either assume linear mobility relationships between Differential Mobility Analyzers (DMAs) or assume experimental distribution shapes (i.e. Gaussian) in order to simplify the inversion process. For some volatility and hygroscopicity experiments, either assumption can be incorrect since TDMA inversions neglect the experimental models during the inversion process. The models are added post inversion which can complicate the interpretation of non-ideal responses.
We present a TDMA forward inversion routine that models the experimental phenomena during the inversion process. These physical models determine the shape of the experimental response, and, ultimately, the shape of the raw output distribution. The new inversion process can create non-ideal responses. Comparing the inversion response to the measured response provides the value of the desired experimental variable (e.g. vapor pressure, hygroscopicity).