@article {4629,
	title = {Gas dynamics of the ICP-MS interface: impact pressure probe measurements of gas flow profiles},
	journal = {Journal of Analytical Atomic Spectrometry},
	volume = {14},
	number = {1},
	year = {1999},
	note = {ISI Document Delivery No.: 159PLTimes Cited: 14Cited Reference Count: 23},
	month = {Jan},
	pages = {9-17},
	type = {Article},
	abstract = {A versatile ICP-vacuum interface was constructed to investigate the gas dynamics and gas flow profiles of the ICP-MS interface. This new interface combines-a low interface pressure, greater than or equal to 0.24 Torr, with the ability to accommodate a variety of skimmer designs at sampler to skimmer spacings up to 80 mm. Plasma beams were extracted by placing a 0.9 or 2.0 mm diameter skimming orifice at distances of 6.7-47 mm behind, the sampling orifice. Gas flow profiles of each resulting plasma beam were measured using an impact pressure probe placed at distances of 35-105 mm behind the skimmer. The centreline flux and width of the gas beam were compared with those calculated for an ideally skimmed beam. The results for the 0.9 mm diameter skimmer orifice showed that placing the skimmer at 11.0 and 27.3 mm downstream of the sampler formed the highest intensity and narrowest beams. In contrast, by placing the skimmer closer to the sampler, as in common interface designs, the beam profile is less intense on the centreline and much wider. Using a larger 2.0 mm diameter Skimming Orifice at 16.5-26.8 mm downstream of the sampler produced a more intense beam than any arrangement using the 0.9 mm skimming orifice. However with the 2.0 mm diameter skimmer, centreline intensities were still about half those of an ideally skimmed beam.},
	keywords = {ION EXTRACTION, PLASMA-MASS-SPECTROMETRY, SPACE-CHARGE, VACUUM INTERFACE},
	isbn = {0267-9477},
	url = {<Go to ISI>://000078182600006},
	author = {Olney, T. N. and Chen, W. and Douglas, D. J.}
}
@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 = {<Go to ISI>://A1991GJ48300005},
	author = {Chen, S. P. and Comisarow, M. B.}
}
