Drift differential mobility analyzer

This work addresses the problem of narrowing the peak diffusive broadening observed in the response of differential mobility analyzers (DMA) when dealing with nanoparticles and ions. Instead of achieving this task by solely increasing the sheath gas flowrate through the instrument (i.e. increasing the Peclet number, Pe), as done in recent studies, we show that the broadening can be further reduced by establishing an axial electric field upon the classical transverse one. This still nonexisting instrument would be what we call a drift-DMA (DDMA). The asymptotic analysis (Pe 1) indicates that a well designed DDMA might triple the resolution of Rosellʹs DMA (Rosell-Llompart et al., J. Aerosol Sci. 27, 695–719) when both instruments run at the same Pe, placing this hypothetic instrument in an excellent position to even compete with standard ion drift tubes. On the other hand, the DDMA would yield the same resolution of a Rosellʹs DMA but running at a Reynolds number Re near one order of magnitude smaller, with the corresponding saving on pumping needs.