@article {2609,
	title = {A laser desorption-electron impact ionization ion trap mass spectrometer for real-time analysis of single atmospheric particles},
	journal = {International Journal of Mass Spectrometry},
	volume = {281},
	number = {3},
	year = {2009},
	note = {ISI Document Delivery No.: 426SSTimes Cited: 3Cited Reference Count: 73Simpson, E. A. Campuzano-Jost, P. Hanna, S. J. Robb, D. B. Hepburn, J. H. Blades, M. W. Bertram, A. K.},
	month = {Apr},
	pages = {140-149},
	type = {Article},
	abstract = {A novel aerosol ion trap mass spectrometer combining pulsed IR laser desorption with electron impact (EI) ionization for single particle studies is described. The strengths of this instrument include a two-step desorption and ionization process to minimize matrix effects; electron impact ionization, a universal and well-characterized ionization technique; vaporization and ionization inside the ion trap to improve sensitivity; and an ion trap mass spectrometer for MSn experiments. The instrument has been used for mass spectral identification of laboratory generated pure aerosols in the 600 nm-1.1 mu m geometric diameter range of a variety of aromatic and aliphatic compounds, as well as for tandem mass spectrometry studies (up to MS3) of single caffeine particles. We investigate the effect of various operational parameters on the mass spectrum and fragmentation patterns. The single particle detection limit of the instrument was found to be a 325 nm geometric diameter particle (8.7 x 10(7) molecules or 22 fg) for 2,4-dihydroxybenzoic acid. Lower single particle detection limits are predicted to be attainable by modifying the El pulse. The use of laser desorption-electron impact (LD-EI) in an ion trap is a promising technique for determining the size and chemical composition of single aerosol particles in real time. (C) 2009 Elsevier B.V. All rights reserved.},
	keywords = {AERODYNAMIC LENSES, Aerosol mass spectrometry, AEROSOL-PARTICLES, CHEMICAL-ANALYSIS, CONTROLLED DIMENSIONS, Electron impact ionization, ENVIRONMENTAL PARTICLES, INVERSE FOURIER-TRANSFORM, LENS-NOZZLE SYSTEM, NUMERICAL CHARACTERIZATION, ORGANIC AEROSOLS, Particle laser, Single particle analysis, THERMAL VAPORIZATION, vaporization},
	isbn = {1387-3806},
	url = {<Go to ISI>://000264728600006},
	author = {Simpson, E. A. and Campuzano-Jost, P. and Hanna, S. J. and Robb, D. B. and Hepburn, J. H. and Blades, M. W. and Bertram, A. K.}
}
@article {1439,
	title = {Does atmospheric processing of saturated hydrocarbon surfaces by NO3 lead to volatilization?},
	journal = {Geophysical Research Letters},
	volume = {33},
	number = {17},
	year = {2006},
	note = {ISI Document Delivery No.: 085ZJTimes Cited: 23Cited Reference Count: 28Knopf, D. A. Mak, J. Gross, S. Bertram, A. K.},
	month = {Sep},
	pages = {5},
	type = {Article},
	abstract = {The heterogeneous oxidation of a saturated hydrocarbon monolayer by NO3 was studied. A flow tube reactor coupled to chemical ionization mass spectrometry was used to determine the reactive uptake coefficient of NO3 on these surfaces, and X-ray photoelectron spectroscopy (XPS) was used to investigate surface oxidation and to determine if exposure to NO3 leads to volatilization of the organic substrate. The uptake coefficient of NO3 by an alkane monolayer is about (8.8 +/- 2.5) x 10(-4), which may lead to competitive oxidation compared with OH, due to the higher atmospheric abundance of NO3 under certain conditions. The XPS results are consistent with the formation of 1) C-O groups, 2) ketones or aldehydes, and 3) carboxylic groups. The XPS results also suggest that NO3 does not rapidly volatilize the organic surface: even under extremely polluted conditions, maximum 10\% of the organic layer is volatilized.},
	keywords = {FILMS, GAS-PHASE PRODUCTS, HETEROGENEOUS REACTION, KINETICS, LIQUID, OLEIC-ACID, ORGANIC AEROSOLS, ozone, PARTICLES, REACTIVE UPTAKE},
	isbn = {0094-8276},
	url = {<Go to ISI>://000240642600004},
	author = {Knopf, D. A. and Mak, J. and Gross, S. and Bertram, A. K.}
}
