Servicenavigation

Project Details

Back

Projekt Print View

Fundamental investigations on the effect of high effective ion temperatures on the ion mobility, cluster formation, dissociation and their dynamics as well as fragmentation by high-resolution, high kinetic energy Ion mobility spectrometry

Subject Area Measurement Systems
Term from 2016 to 2023
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 318063177
 
Final Report Year 2023

Final Report Abstract

Besides the very challenging hardware implementation of a High Kinetic Energy Ion Mobility Spectrometer (HiKE-IMS) with high resolving power, fundamental investigations of HiKE-IMS and the gas phase reactions in HiKE-IMS have been advanced during the project. Compared to classical IMS, HiKE-IMS is characterized by its low operating pressure of 10 to 40 mbar, so that chemical ionization, cluster formation and dissociation as well as fragmentation can be controlled in a targeted manner by the energy level of the ions. This is scientifically extremely interesting, but also significantly improves reliability of substance identification in real applications. Moreover, by controlling the ionization process, substances that cannot be ionized in classical IMS by chemical gas phase ionization, such as benzene, are now detectable down to the single-digit ppbV range. The energy level can be expressed either in terms of the reduced electric field strength E/N, with the electric field strength E and the particle density N, or as the effective ion temperature, which is defined by the reduced electric field strength and the absolute temperature. Investigating the ion mobility at different E/N and different absolute temperatures while keeping the effective ion temperature constant has shown that just the effective ion temperature defines the ion mobility. Furthermore, the resulting reactant ion population in HiKE-IMS has been investigated for different operating parameters, such as pressure and E/N, and an analytical model for the number of available reactant ions generated by corona discharge has been developed. With the help of an analytical model for the resolving power of HiKE-IMS considering all relevant effects, a HiKE-IMS with high resolving power > 200 could be realized for the first time. With this device, it is possible to separate isotopologues with all carbon atoms replaced by 13C atoms, although such isotopologues have identical structure and thus identical collision cross section. On a technical level, it should be noted that besides setting up different HiKE-IMS, a novel ion gate concept including the driver electronics has been developed. With this ion gate, narrow ion packets can be transferred into the drift region without any discrimination of slow ions even at extremely short gate opening times of just 1 µs. The principle of this ion gate is now also used in IMS with electrospray ionization for sensitive detection of large ions even at short ion gate opening times as required for high resolving power.

Publications

 
 

Additional Information

© 2025 DFG Disclaimer / Copyright / Privacy Policy

Textvergrößerung und Kontrastanpassung