@article {2232,
	title = {Investigation of substituted-benzene dopants for charge exchange ionization of nonpolar compounds by atmospheric pressure photoionization},
	journal = {Journal of the American Society for Mass Spectrometry},
	volume = {19},
	number = {7},
	year = {2008},
	note = {ISI Document Delivery No.: 329LWTimes Cited: 7Cited Reference Count: 24Robb, Damon B. Smith, Derek R. Blades, Michael W.},
	month = {Jul},
	pages = {955-963},
	type = {Article},
	abstract = {Atmospheric pressure photoionization (APPI) using a dopant enables both polar and nonpolar compounds to be analyzed by LC/MS. To date, the charge exchange ionization pathway utilized for nonpolar compounds has only been efficient under restrictive conditions, mainly because the usual charge exchange reagent ions-the dopant photoions themselves-tend to be consumed in proton transfer reactions with solvent and/or dopant neutrals. This research aims to elucidate the factors affecting the reactivities of substituted-benzene dopant ions; another, overriding, objective is to discover new dopants for better implementing charge exchange ionization in reversed-phase LC/MS applications. The desirable properties for a charge exchange dopant include low reactivity of its photoions with solvent and dopant neutrals and high ionization energy (IE). Reactivity tests were performed for diverse substituted-benzene compounds, with substituents ranging from strongly electron withdrawing (EW) to strongly electron donating (ED). The results indicate that both the tendency of a dopant{\textquoteright}s photoions to be lost through proton transfer reactions and its IE depend on the electron donating /withdrawing properties of its substituent(s): ED groups decrease reactivity and IE, while EW groups increase reactivity and IE. Exceptions to the reactivity trend for dopants with ED groups occur when the substituent is itself acidic. All told, the desirable properties for a charge exchange dopant tend towards mutual exclusivity. Of the singlysubstituted benzenes tested, chloro- and brornobenzene provide the best compromise between low reactivity and high IE. Several fluoroanisoles, with counteracting EW and ED groups, may also provide improved performance relative to the established dopants.},
	keywords = {APPI, MASS-SPECTROMETRY, MECHANISM, MS, POTENTIALS, PROTON AFFINITY, SOLVENT},
	isbn = {1044-0305},
	url = {<Go to ISI>://000257870100007},
	author = {Robb, D. B. and Smith, D. R. and Blades, M. W.}
}
@article {4229,
	title = {Accurate density functional calculation of core-electron binding energies with a scaled polarized triple-zeta basis set. IV. Application to isomers of C3H6O, C3H3NO, and C6H6},
	journal = {Journal of Chemical Physics},
	volume = {108},
	number = {21},
	year = {1998},
	note = {ISI Document Delivery No.: 108FRTimes Cited: 21Cited Reference Count: 62},
	month = {Jun},
	pages = {8950-8956},
	type = {Article},
	abstract = {The unrestricted generalized transition-state model using a gradient-corrected density functional was shown in previous papers to be a reliable procedure for calculating core-electron binding energies. Relativistic corrections were estimated. Recently, a more efficient basis was proposed and tested. The results indicated that the new scaled polarized valence triple-zeta basis performs as well as the much larger cc-pV5Z basis set. This procedure is followed in the present study of the known isomers of C3H6O, C3H3NO, and C6H6. The results demonstrate that x-ray photoelectron spectroscopy, complemented by accurate theoretical calculations, can indeed be used to help chemical analysis. (C) 1998 American Institute of Physics. [S0021-9606(98)00721-1]},
	keywords = {APPROXIMATION, ATOMS, ELECTRONEGATIVITY, ESCA, GAS, MICROWAVE-SPECTRUM, MOLECULES, PHOTOELECTRON-SPECTROSCOPY, PROTON AFFINITY, STATES},
	isbn = {0021-9606},
	url = {<Go to ISI>://000075255900021},
	author = {Chong, D. P. and Hu, C. H.}
}
