Improved First-Principles Model of Differential Mobility Using Higher Order Two-Temperature Theory.

Area of Science:

• Analytical Chemistry
• Physical Chemistry

Background:

• Differential mobility spectrometry (DMS) separates diverse analytes.
• Existing theoretical models for DMS often neglect dynamic microsolvation effects.
• Accurate theoretical descriptions are needed for complex analytes and environments.

Purpose of the Study:

• To advance theoretical models of differential ion mobility.
• To incorporate higher-order corrections and ion-neutral interaction models.
• To improve prediction accuracy for various compounds in different environments.

Main Methods:

• Applied higher order corrections to two-temperature theory (2TT).
• Utilized a pseudoequilibrium approach for ion-neutral interactions.
• Validated model predictions against experimental dispersion plots for over 300 compounds.

Main Results:

• Higher-order 2TT corrections reduced prediction errors by approximately 50%.
• Model achieved high accuracy in pure N2 environments (mean absolute error of 4 V at SV = 4000 V).
• General trends of clustering strength, solvent concentration, and temperature were well reproduced.

Conclusions:

• The refined theoretical model offers improved predictions for differential ion mobility.
• Accurate thermochemical corrections are crucial for strongly clustering environments.
• The study provides insights into ion-solvent clustering dynamics in DMS.