Recent results on the formation and spectroscopy of solvated peptide ions will be presented and discussed. These studies utilize a new experimental approach that affords well-controlled ion-molecule reactions between, and solvent clustering around, gaseous ions. This recently developed apparatus combines an electrospray ionization source to access a wide variety of molecules of interest, two temperature-controlled cryogenic ion traps for sequential ion manipulations, and a time-of-flight infrared photofragmentation mass spectrometer to acquire well-resolved IR action spectra. Therefore, the precursor ions formed by ESI are selectively modified in the cryogenic ion traps and structurally probed by infrared predissociation spectroscopy. This talk will present the structural evolution of GlyH+, GlyGlyH+ and GlyGlyGlyH+ ions as a function of stepwise solvation and show how the presence of just a few water molecules can significantly influence the geometry of these model peptides that possess varying degrees of structural flexibility. The cryogenic ion trap also affords fine-tuning of the reaction temperatures during clustering, thereby providing control over the extent of gas-phase H/D exchange between D2O and peptide ion. This yields additional spectroscopic information which can be used to facilitate the interpretation of the increasingly congested spectra as the complexity the ion and the size of the solvent clusters are increased.

Controlled cluster formation and spectroscopic characterization of microsolvated model peptides

256th National Meeting (2018)

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