Effect of Acoustic Radiation on DMA Resolution

Figures & data

FIG. 1 Full width at half height (FWHH) versus peak voltage for the transfer function of the DMA of Rosser et al. (2005) when classifying tetraheptyl ammonium ions. Note the resonance arising at about 410 volts, attributed to acoustic radiation.

Table 1 Electrical mobility of the three ions used

Ion	ethyl4N^+	butyl4N^+	heptyl4N^+
Z (cm^2/V/s)	1.79	1.39	0.96
Source: Ude et al. 2005.

FIG. 2 Performance of the Río Arriba DMA (RA) with three different ions. Note the dip down to almost ideal behavior near the sonic point (rightmost datum for each ion). (a) FWHH versus voltage (volt); (b) FWHH/Z^1/2 versus Re^1/2, with Z in cm²/V/s.

FIG. 3 Mobility spectra for the tetraheptyl ammonium ion in the Herrmann DMA. While pumping power increases monotonically from left to right, the peak positions exhibit a saturation phenomenon indicating that sonic conditions have been reached. V_p is in volts.

FIG. 4 FWHH versus peak voltage for the Herrmann DMA, using either methyl₄N⁺ ions (a), or ethyl₄N⁺ (b). V_p is in volts.

FIG. 5 Resolution of the Herrmann DMA in a representation similar to that of Figure 2b, separating the flow effects in the horizontal variable. This variable is now the Mach number in the working section, showing with greater clarity the transonic increase in resolution.

Rosser , S. and Fernández de la Mora , J. 2005 . Vienna-Type DMA of High Resolution and High Flow Rate . Aerosol Sci. Technol. , Submitted to, 24/Nov/2004[CSA]

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