Molecular Structure Characterization by Isotopic Splitting in Nonlinear Ion Mobility Spectra

Area of Science:

• Analytical Chemistry
• Physical Chemistry
• Spectroscopy

Background:

• Compounds contain isotopologues from stable isotopes.
• Isotopic envelopes in mass spectra show stoichiometry, not geometry.
• Distinguishing isomers is a persistent challenge in chemical analysis.

Purpose of the Study:

• To investigate the potential of differential ion mobility spectrometry (DIMS) for isomer characterization.
• To explore the influence of ion geometry and buffer gas on isotopologue splitting in DIMS.
• To establish a novel method for chemical structure elucidation using isotopic shifts.

Main Methods:

• Utilizing differential ion mobility spectrometry (DIMS) coupled with mass spectrometry.
• Analyzing the splitting patterns of isotopologue envelopes in DIMS spectra.
• Varying buffer gas composition to observe effects on ion mobility and isotopic shifts.
• Investigating the additivity of observed isotopic shifts.

Main Results:

• Isotopic envelopes split in DIMS spectra, dependent on ion geometry and buffer gas.
• The multidimensional matrix of isotopic shifts is isomer-specific.
• Observed shifts demonstrate additivity, suggesting predictable behavior.
• This effect provides a new dimension for distinguishing chemical structures.

Conclusions:

• Differential ion mobility spectrometry (DIMS) offers a novel approach for isomer characterization.
• Isotopic shift patterns in DIMS are sensitive to ion geometry and buffer gas composition.
• The additivity of shifts may unlock fundamental insights into ion-molecule interactions and chemical structure determination.