Excitations quadrupolar

These, and similar data for other systems, demonstrate the tremendous potential that the MICR technique has for the qualitative elucidation of potential energy surfaces of relatively complex organic reactions. Once implementation of the quadrupolar excitation technique has been effected to relax ions to the cell center, the technique will become even more powerful, in that the determination of highly accurate unimolecular decomposition lifetimes of chemically activated intermediates will also become possible. No other technique offers such a powerful array of capabilities for the study of unimolecular dissociation mechanisms and rates. 

FIGURE 6.3 The time-of-flight of the ions versus the quadrupolar excitation frequency. The cyclotron resonance frequency is determined from the position of the dip. 

Justification for using two-plate quadrupolar excitation has been reported by several groups including Jackson et al. who demonstrated the qualitatively similar results of a mixture of PEG 1000 and PEG 1500 undergoing both two-plate and four-plate ion axialization. The authors note that despite the complex dynamics and interacting resonances produced from a two-plate excitation, the results show similar efficiencies in their ability to cool ions. 

Pitsenberger, C. C., Easterling, M. L., and Amster, I. J., "Effects of Capacitive Coupling on Ion Remeasurement Using Quadrupolar Excitation in High-Resolution FTICR Spectrometry," Anal. Chem., 68, 4409M413,1996. 

Pastor, S. J., Gastoro, J. A., and Wilkins, C. L., High-Mass Anal3 is Using Quadrupolar Excitation/Ion Cooling in a Fourier Transform Mass Spectrometer, Anal. Chem., 67, 379, 1995. 

Together with eq. (A7) this defines the dispersion of collective quadrupolar excitations that is given by the zeros of the denominator in eq. (A7). The renormalized phonon propagator is now obtained by Dyson s equation (fig. 59a)... 

Pitsenberger, C.C., Easterling, M.L., and Amster, I.J. (1996) Effects of capacitive coupling on ion remeasurement using quadrupolar excitation in high-resolution FTICR spectrometry. Anal. 

Figure 11.16. Illustration of the applied waveforms for dipolar versus quadrupolar excitation. (A) For dipolar excitation, opposite phases of the excitation waveform is applied to opposing excite plates. (B) Four excite plates are used for quadrupolar excitation, with opposing pairs of plates applying the same polarity but with adjacent plates having opposite polarity. The symmetry of the resulting electric field is dipolar in A and quadrupolar i n B. (Adapted from Ref. 161.)...

Schweikhard, L. Guan, S. H. Marshall, A. G. Quadrupolar excitation and colUsional cooling for axialization and high-pressure trapping of ions in Fourier-transform ion-cyclotron resonance mass-spectrometry. Int. J. Mass Spectrom. Ion Processes 1992, 120, 71-83. 

Speir, j. P Gorman, G. S. Pitsenberger, C. C. Turner, C. A. Wang, P. P Amster, 1. J. Remeasurement of ions using quadrupolar excitation Fourier-transform ion-cyclotron resonance spectrometry. Anal. Chem. 1993, 65, 1746-1752. 

Hendrickson, C. L. Drader, J. J. Laude, D. A. Simplified application of quadrupolar excitation in Fourier transform ion cyclotron resonance mass spectrometry. J. Am. Soc. Mass. Spectrom. 1995, 6, 448-452. 

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