@article {2693,
	title = {Field distribution in an electrospray ionization source determined by finite element method},
	journal = {Rapid Communications in Mass Spectrometry},
	volume = {23},
	number = {5},
	year = {2009},
	note = {ISI Document Delivery No.: 413LQTimes Cited: 2Cited Reference Count: 17Zhong, Xuefei Yi, Rong Holliday, Alison E. Chen, David D. Y.},
	month = {Mar},
	pages = {689-697},
	type = {Article},
	abstract = {Three-dimensional computer models of electrospray ionization sources were constructed in COMSOL Multiphysics (TM) to solve the static electric fields using finite element methods. The magnitude of the electric field strength for onset of electrospray and optimum signal was calculated under various conditions. The modification of the electric field distribution in the ion source by an atmospheric pressure ion lens was also investigated by plotting the equipotential surfaces, electric field lines and trajectories of charged droplets. Both the calculated and the experimental results demonstrate that the changes in the ion signal detected by the mass spectrometer are attributable to the focusing effect of the ion lens when appropriate voltages are applied on the sprayer and ion lens. The optimum signal was found by setting the sprayer voltage from 3000 to 5000 V while scanning the ion lens voltage. The calculated strengths of the electric field at the sprayer tip for optimum signals are similar although the applied voltages at the sprayer and ion lens are significantly different. Copyright (C) 2009 John Wiley \& Sons, Ltd.},
	keywords = {ION-SOURCE},
	isbn = {0951-4198},
	url = {<Go to ISI>://000263795000019},
	author = {Zhong, X. F. and Yi, R. and Holliday, A. E. and Chen, D. D. Y.}
}
@article {1237,
	title = {Effects of solvent flow, dopant flow, and lamp current on dopant-assisted atmospheric pressure photoionization (DA-APPI) for LC-MS. Ionization via proton transfer},
	journal = {Journal of the American Society for Mass Spectrometry},
	volume = {16},
	number = {8},
	year = {2005},
	note = {ISI Document Delivery No.: 952BFTimes Cited: 42Cited Reference Count: 37},
	month = {Aug},
	pages = {1275-1290},
	type = {Article},
	abstract = {In this paper, the effects of solvent flow, dopant flow, and lamp power on proton transfer ionization in dopant-assisted (DA) atmospheric pressure photoionization (APPI) are investigated. A broad theoretical framework is presented, describing the primary photoionization process, the formation of protonated-solvent cluster ions, and the balance between analyte ion creation via proton transfer and loss via recombination. The principal experimental test system utilized methanol as the solvent, toluene as the dopant, and acridine as the analyte. Comparisons are made between acridine and a less basic compound, 9-methylanthracene (9-MA). Experimental determinations of the trends in the analyte MH+ signal and the total ion current (TIC) with variations in the subject parameters are provided. Experimental results and theory demonstrate that both the analyte signal and the TIC approach asymptotic limits with increases in dopant flow and/or lamp current (two factors which dictate the rate of photoion generation). The data show that these limits are lowered at higher solvent flow rates. These results are attributed to the recombination loss process, the rate of which increases with the second power of ion concentration. We deduce that the recombination rate constant increases with solvent flow rate, a consequence of the growth of ion-solvent clusters. Cluster growth is also believed to be a factor in the dramatic loss of sensitivity for 9-MA that occurs as the solvent flow is raised, because larger protonated-solvent cluster ions have greater solvation energies and may be unreactive with compounds having low gas-phase basicity and/or low solvation energy.},
	keywords = {DETECTOR, GAS-PHASE, ION-SOURCE, LIQUID-CHROMATOGRAPHY, MASS-SPECTROMETRY, METHANOL, PLASMA, SENSITIVITY, SOLVATION, SYSTEM},
	isbn = {1044-0305},
	url = {<Go to ISI>://000230975700009},
	author = {Robb, D. B. and Blades, M. W.}
}
@article {7175,
	title = {ATOMIC EXCITATION IN A JET-ASSISTED GLOW-DISCHARGE PLASMA PLUME},
	journal = {Spectrochimica Acta Part B-Atomic Spectroscopy},
	volume = {47},
	number = {11},
	year = {1992},
	note = {ISI Document Delivery No.: JN613Times Cited: 9Cited Reference Count: 41},
	month = {Oct},
	pages = {1287-1307},
	type = {Article},
	abstract = {A jet-assisted glow discharge emission source has previously been shown to suffer from self-absorption when the viewing axis is orientated in line with the support gas flow. This problem can be alleviated by rotating the viewing axis 90-degrees so that the absorption path length is significantly reduced; however, in viewing side-on, line-of-sight measurements of the plasma plume can be accomplished no closer than 25 mm from the sample surface due to geometry limitations. At this axial distance from the sample, the plume shows no Ar 11 emission, which differentiates it from the negative glow. Furthermore. evidence was found that the plume possesses features similar to flowing afterglows: energy is transported from the negative glow to the plume through argon metastable atoms. The collision of two metastable argon atoms produces ionization to the ground state of the argon ion, deactivation to the ground state of the argon atom and an energetic electron (7.32-7.68 eV) which is capable of exciting sputtered atoms. A strong correlation is observed between the square of the argon metastable population and the emission intensity for Cu I and Zn I as the jet flow rate is manipulated.},
	keywords = {ARGON, ICP, ION-SOURCE, LAMP, MASS-SPECTROMETRY, PERFORMANCE, STATE},
	isbn = {0584-8547},
	url = {<Go to ISI>://A1992JN61300005},
	author = {Banks, P. R. and Blades, M. W.}
}
