Mass–Mobility Measurements Using a Centrifugal Particle Mass Analyzer and Differential Mobility Spectrometer

Figures & data

FIG. 1 Experimental set-up for neutralizer–CPMA–DMS system where:

is the DMS classifier sample flow rate,

is the DMS classifier sheath flow rate,

is the DMS charger temperature,

is the DMS classifier temperature, and

is the DMS classifier pressure.

FIG. 2 Correction method to remove the effects of multiply charged particles and apply the size calibration to CPMA–DMS measurements. The subfigures illustrate the results for one data point and depict the: (a) unclassified aerosol mobility size distribution, (b) CPMA-classified mobility size distribution including uncharged particles, (c) CPMA-classified mobility size distribution, (d) unscaled DMS model ring currents, (e) scaled DMS model ring currents, (f) multiply charged corrected standard DMS ring currents, (g) multiply charged corrected modified DMS ring currents, and (h) multiply charged corrected size distribution fitted with a lognormal curve.

FIG. 3 (a) Measured effective density of DEHS using a CPMA with a resolution of 3 and modified DMS system, applying the Wiedensohler bipolar charging model within the correction process. (b) Comparison of DEHS effective density values calculated from the data described in (a) with: (i) no correction, (ii) size calibration only, (iii) multiple-charge correction only, and (iv) multiple-charge correction and size calibration.

FIG. 4 (a) Measured effective density of DEHS using CPMA with a resolution of 10 and standard DMS system, applying the Wiedensohler bipolar and Fuchs unipolar charging models within the correction process. (b) Comparison of DEHS effective density values calculated from the data described in (a) with: (i) no correction, (ii) size calibration only, (iii) multiple-charge correction only, and (iv) multiple-charge correction and size calibration.

FIG. 5 DEHS-measured effective density using all three standard DMS models where the current generated by uncharged particles was manually removed for all cases, a CPMA resolution of 10 was used, and Wiedensohler bipolar and Fuchs unipolar charging models were applied within the correction process.

FIG. 6 DEHS-measured effective density found by manually and automatically removing the current generated by uncharged particles in the standard DMS system (using DMS model 1 for both cases).