Authors: J Larry Campbell Mabel Zhu W Scott Hopkins
Publish Date: 2014/07/08
Volume: 25, Issue: 9, Pages: 1583-1591
Abstract
Differential mobility spectrometry DMS can distinguish ions based upon the differences in their high and lowfield ion mobilities as they experience the asymmetric waveform applied to the DMS cell These mobilities are known to be influenced by the ions’ structure m/z and charge distribution ie resonance structures within the ions themselves as well as by the gasphase environment of the DMS cell While these associations have been developed over time through empirical observations the exact role of ion structures or their interactions with clustering molecules remains generally unknown In this study that relationship is explored by observing the DMS behaviors of a series of tetraalkylammonium ions as a function of their structures and the gasphase environment of the DMS cell To support the DMS experiments the basinhopping search strategy was employed to identify candidate cluster structures for density functional theory treatment More than a million cluster structures distributed across 72 different ionmolecule cluster systems were sampled to determine global minimum structures and cluster binding energies This joint computational and experimental approach suggests that cluster geometry in particular ionmolecule intermolecular separation plays a critical role in DMSThe authors gratefully acknowledge high performance computing support from the SHARCNET consortium of Compute Canada The authors acknowledge financial support from the Natural Sciences and Engineering Research Council NSERC of Canada for financial support in the form of a Discovery grant and an ENGAGE grant EGP 44935413 The authors thank Mr John Lape for help with computational aspects of this study They also thank Professor Scott McLuckey Purdue University and Professor Terry McMahon University of Waterloo as well as Dr Bradley Schneider and Dr Yves Le Blanc AB SCIEX for helpful conversations and critical review of this manuscript
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