Papadopoulos, GeorgiosSvendsen, AnnetteBoyarkin, Oleg V.Rizzo, Thomas R.2011-01-202011-01-202011-01-20201110.1039/C0FD00004Chttps://infoscience.epfl.ch/handle/20.500.14299/63187WOS:000292977100013We describe here experiments that combine differential ion mobility, which separates conformational isomers of biomolecular ions, with electronic spectroscopy in a cold, radio-frequency ion trap. Although the low temperature attainable in a cold ion trap greatly simplifies the electronic spectra of large molecules, conformational heterogeneity can still be a significant source of congestion, complicating spectroscopic analysis. We demonstrate here that using differential ion mobility to separate gas-phase peptide conformers before injecting them into a cold ion trap allows one to decompose a dense spectrum into contributions from different conformational families. In the inverse sense, cold ion spectroscopy can be used as a conformation-specific detector for ion mobility, allowing one to separate an unresolved peak into contributions from different conformational families. The doubly protonated peptide bradykinin serves as a good test case for the marriage of these two techiques as it exhibits a considerable degree of conformational heterogeneity that results in a highly congested electronic spectrum. Our results demonstrate the feasiblity and advantages of directly coupling ion mobility with spectroscopy and provide a diagnostic of conformational isomerization of this peptide after being produced in the gas phase by electrospray.laser spectroscopymass spectrometryion mobilitytext::journal::journal article::research article