@article {6986,
title = {SIMPLE PHYSICAL MODELS FOR COULOMB-INDUCED FREQUENCY-SHIFTS AND COULOMB-INDUCED INHOMOGENEOUS BROADENING FOR LIKE AND UNLIKE IONS IN FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE MASS-SPECTROMETRY},
journal = {Rapid Communications in Mass Spectrometry},
volume = {5},
number = {10},
year = {1991},
note = {ISI Document Delivery No.: GJ483Times Cited: 54Cited Reference Count: 20},
month = {Oct},
pages = {450-455},
type = {Article},
abstract = {Two simple models which correspond more closely to physical reality than some prior models are proposed to account for the Coulomb-induced frequency shifts to lower frequency, which have been observed in Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. The first model consists of two different-mass point charges which undergo cyclotron orbits with the same orbit centers at their respective cyclotron frequencies. The model predicts that each excited cyclotron motion should induce a negative frequency shift in the other{\textquoteright}s cyclotron motion. The model predicts a zero frequency shift for ions of the same mass. The physical basis for the Coulomb-induced shift is most easily seen in a coordinate frame which rotates at the cyclotron motion of the ion whose frequency is shifted. It is noted that a prior model for Coulomb-induced frequency shifts is more appropriate for scanning ICR than FT-ICR and the reason is described for the correctness of the predictions of this less appropriate model. A second model, the line model, is created by extension of the point model. The line model gives rise to a position-dependent frequency shift which is synonymous with inhomogeneous Coulomb broadening. When a non-quadrupolar electrostatic trapping field is included in the model, {\textquoteright}like{\textquoteright} ions become {\textquoteright}unlike{\textquoteright} and Coulomb-shifting and Coulomb-broadening apply, as for {\textquoteright}like{\textquoteright} ions. The analysis predicts that ICR cells which are designed to have negligible trapping fields over most of their volume will be less sensitive to Coulomb shifting/broadening than ordinary ICR cells.},
keywords = {cell, SPACE-CHARGE},
isbn = {0951-4198},
url = {://A1991GJ48300005},
author = {Chen, S. P. and Comisarow, M. B.}
}