## Keywords

Field asymmetric ion mobility spectrometry | |

Differential mobility spectrometry | |

Monte-Carlo simulation | |

Ion transport in gases | |

SIMION |

= user generated What's this?

## Caption

## Extracts from the Article What's this?

In a DMS analyzer, an asymmetric periodic voltage,
*V(t)*, which should satisfy the following condition [3], is
applied to the filtration gap [Fig. 1(a)]: 2 $$ \int_0^\tau
{V(t)dt} = 0, $$ where *τ* is the period of the pulsed
electric field.

*V(t)* can be a time-dependent square waveform consisting of
a high voltage (*V*_{H} ) having a
duration of τ_{H} (referred as high-field phase) and a low
voltage (*V*_{L} ) having a duration of
τ_{L} with the opposite polarity to *V*_{H} (referred to low-field phase), as shown in
Fig. 1(b).

The X component (v_{gX}) of the gas velocity is a function
of the coordinate Y and is given by the following parabolic
distribution [18] 18 $$ \begin{gathered} \begin{array}{*{20}{c}}
{{v_{gX}} = \frac{{3Q}}{{2A}}\left( {1 - \frac{{4{y^2}}}{{{d^2}}}}
\right)} & { - 0.5d<y<0.5d} \\ \end{array} \hfill \\
\hfill \\ \end{gathered} $$ where Q is the flow rate, A is the
cross section area of the gap perpendicular to the gas flow, d is
the gap height, and y is the coordinate originated in the center of
the gap, as shown in Fig. 1.

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### Monte Carlo simulation of ion transport in non-linear ion mobility spectrometry

by
Xu, Jun; Liu, Yuan**Journal:** International Journal for Ion Mobility Spectrometry
**Vol.** 12
**Issue** 4**DOI:** 10.1007/s12127-009-0029-6**Published:** 2009-11-11**Institution(s):**
Oak Ridge National Laboratory

Abstract

A program for Monte Carlo simulation of ion transport in non-linear ion mobility spectrometry, also known as field asymmetric ion mobility spectrometry (FAIMS) or differential mobility spectrometry (DMS), has been developed. Simulations are based on elastic collisions between the ions and the gas particles, and take into account the effects of flow dynamics and asymmetric electric fields. Using this program, the separation and diffusion of the ions moving in a planar DMS filtration gap are demonstrated. Ion focusing in a cylindrical filtration gap is also confirmed. A characteristic compensation voltage is found to provide insight for understanding separation in non-linear ion mobility spectrometry. The simulation program is used to study the characteristics of non-linear ion mobility spectrometry, the effect of the carrier gas flow, and the dependence of the compensation voltage and nonlinear mobility coefficient (α) on the applied asymmetric electric field.

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