@article {1529,
	title = {Factors affecting primary ionization in dopant-assisted atmospheric pressure photoionization (DA-APPI) for LC/MS},
	journal = {Journal of the American Society for Mass Spectrometry},
	volume = {17},
	number = {2},
	year = {2006},
	note = {ISI Document Delivery No.: 012ZFTimes Cited: 25Cited Reference Count: 20},
	month = {Feb},
	pages = {130-138},
	type = {Article},
	abstract = {The sensitivity of dopant-assisted atmospheric pressure photoionization (DA-APPI) for LC/MS is generally reduced at higher solvent flow rates. Theory suggests that quenching of excited-state precursors to the dopant ions, via collisions with vaporized solvent molecules, may be one mechanism responsible for this trend. To ascertain if the primary rate of ionization is affected by quenching, experiments were performed utilizing an ionization detector to determine the primary ion current generated by irradiating vaporized mixtures of toluene dopant and methanol solvent. The results indicate that no loss of primary ion current occurs as the solvent flow is increased, provided the dopant-to-solvent ratio is held constant. Additional primary ion current can always be generated by increasing the dopant flow rate and/or the lamp power. Thus, quenching of excited-state precursors to the dopant ions, leading to a reduction in the primary rate of ionization, is not the mechanism responsible for the observed loss of sensitivity at higher liquid solvent flow rates.},
	keywords = {DETECTOR, LIQUID-CHROMATOGRAPHY, MASS-SPECTROMETRY, PERFORMANCE, PLASMA, SOLVENT FLOW},
	isbn = {1044-0305},
	url = {<Go to ISI>://000235378700003},
	author = {Robb, D. B. and Blades, M. W.}
}
@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 {4112,
	title = {Atmospheric pressure, radio frequency, parallel plate capacitively coupled plasma - excitation temperatures and analytical figures of merit},
	journal = {Spectrochimica Acta Part B-Atomic Spectroscopy},
	volume = {52},
	number = {13},
	year = {1997},
	note = {ISI Document Delivery No.: YR110Times Cited: 15Cited Reference Count: 45},
	month = {Nov},
	pages = {1983-1993},
	type = {Article},
	abstract = {Electronic excitation (T-exc) and rotational (T-rot) temperatures were determined for a parallel plate capacitively coupled rf plasma operating at atmospheric pressure. T-exc was calculated from the slope of the Boltzmann plot using Fe and He as the thermometric species and Ph excitation temperature was calculated using the two line method. Over a power range from 100 W to 250 W, excitation temperatures are 3255-3900 K for He, 3540-4500 K for Pb, and 4300-4890 K for Fe. The rotational temperature was measured using both OK and N-2(+) molecular spectra and the values are in the range of 828-911 K and 845-956 K respectively over a power range of 75-275 W. Signal-to-noise ratios, signal-to-background ratios, and absolute detection limit for lead (0.33 ng) and silver (24 pg) are also reported. (C) 1997 Elsevier Science B.V.},
	keywords = {ATOMIC EMISSION-SPECTROMETRY, capacitively coupled plasma, CHARGE-TRANSFER, DETECTOR, DISCHARGE, excitation temperature, FAPES, GAS, HELIUM PLASMA, HELIUM PLASMAS, metals, MICROWAVE-INDUCED PLASMA, rotational temperature, SPECTROSCOPY},
	isbn = {0584-8547},
	url = {<Go to ISI>://000071459300008},
	author = {Rahman, M. M. and Blades, M. W.}
}
@article {2965,
	title = {ATMOSPHERIC-PRESSURE, RADIO-FREQUENCY, CAPACITIVELY COUPLED HELIUM PLASMAS},
	journal = {Spectrochimica Acta Part B-Atomic Spectroscopy},
	volume = {49},
	number = {1},
	year = {1994},
	note = {ISI Document Delivery No.: MX741Times Cited: 25Cited Reference Count: 42},
	month = {Jan},
	pages = {47-57},
	type = {Article},
	keywords = {ATOMIC EMISSION-SPECTROSCOPY, DETECTOR, EXCITATION SPECTROMETRY, FAPES, FURNACE, LEAD, POWER},
	isbn = {0584-8547},
	url = {<Go to ISI>://A1994MX74100006},
	author = {Blades, M. W.}
}
@article {7034,
	title = {CHARACTERIZATION OF AN ATMOSPHERIC-PRESSURE PARALLEL-PLATE CAPACITIVELY COUPLED RADIOFREQUENCY PLASMA},
	journal = {Applied Spectroscopy},
	volume = {45},
	number = {9},
	year = {1991},
	note = {ISI Document Delivery No.: GR646Times Cited: 17Cited Reference Count: 37},
	month = {Nov},
	pages = {1468-1477},
	type = {Article},
	abstract = {A new design for a radio-frequency, atmospheric-pressure, parallel-plate capacitively coupled plasma (CCP) which uses water-cooled electrodes is described. Four different sizes of quartz tubes were compared with respect to spatial emission features for support gas and analyte species. Torches studied had the following inside dimensions: a 1-mm capillary tube with round cross section, a 2 x 4 mm tube, a 4 x 4 mm tube, and a 6 x 6 mm tube. Relative emission intensities of near-infrared lines for F, Cl, Br, I, C, N, and O atomic and ionic lines excited with the use of the He-CCP are tabulated. The detection limits range from 10 to 78 pg/s.},
	keywords = {ARGON, ATOMIC EMISSION SPECTROSCOPY, capacitively coupled plasma, CHLORINE, DETECTOR, EXCITATION, GAS-CHROMATOGRAPHIC, HELIUM PLASMA, MICROWAVE-INDUCED PLASMA, NEAR-INFRARED EMISSION, NONMETAL ATOMIC EMISSION, RED, SPECTRA, SPECTROMETRY},
	isbn = {0003-7028},
	url = {<Go to ISI>://A1991GR64600012},
	author = {Huang, D. G. and Blades, M. W.}
}
