A compact high-resolution X-ray ion mobility spectrometer.

Abstract

For the ionization of gaseous samples, most ion mobility spectrometers employ radioactive ionization sources, e.g., containing (63)Ni or (3)H. Besides legal restrictions, radioactive materials have the disadvantage of a constant radiation with predetermined intensity. In this work, we replaced the (3)H source of our previously described high-resolution ion mobility spectrometer with 75 mm drift tube length with a commercially available X-ray source. It is shown that the current configuration maintains the resolving power of R = 100 which was reported for the original setup containing a (3)H source. The main advantage of an X-ray source is that the intensity of the radiation can be adjusted by varying its operating parameters, i.e., filament current and acceleration voltage. At the expense of reduced resolving power, the sensitivity of the setup can be increased by increasing the activity of the source. Therefore, the performance of the setup can be adjusted to the specific requirements of any application. To investigate the relation between operating parameters of the X-Ray source and the performance of the ion mobility spectrometer, parametric studies of filament current and acceleration voltage are performed and the influence on resolving power, peak height, and noise is analyzed.