SORI Excitation: Collisional and Radiative Processes

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Theoretical modeling of sustained off-resonance irradiation collision-induced dissociation (SORI-CID) experiments in Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry is described in the present paper. Manipulation of various analytical expressions yield the result that the average laboratory frame collision energy is equal to 2/3 of the maximum kinetic energy in SORI. Survival yields (the fraction of nondecomposed molecular ions) as a function of excitation time, collision energy, and source temperature have been considered: results of MassKinetics-type reaction kinetics modeling were compared with experimental results obtained by Guo et al. (Int. J. Mass Spectrom. 2003, 225, 71-82). The results show that radiative cooling has a major influence in SORI-CID. They also suggest that collisional cooling is significant only at very low (less than 0.02 eV) center of mass collision energy; therefore it has a very small influence on the SORI process. Survival yield curves showed excellent agreement between experiments and calculations optimizing two parameters only (collisional energy-transfer efficiency and radiative cooling rate). Using leucine enkephalin as a model compound, the results indicate 0.128 ± 0.021 energy deposition in a single collision and 7.5 ± 0.5 s-1 infrared cooling rate. We also present that these two physical parameters cannot be properly deconvoluted. This effect shows the importance of the parallel consideration of different physical processes.

Original languageEnglish
Pages (from-to)2119-2126
Number of pages8
JournalJournal of the American Society for Mass Spectrometry
Issue number12
Publication statusPublished - Dec 1 2007

ASJC Scopus subject areas

  • Structural Biology
  • Spectroscopy

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