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Environ Sci Technol

Title:		Nucleation particles in diesel exhaust: composition inferred from in situ mass spectrometric analysis
Author(s):		Schneider J; Hock N; Weimer S; Borrmann S; Kirchner U; Vogt R; Scheer V;
Address:		"Cloud Physics and Chemistry Department, Max Planck Institute for Chemistry, Johannes Gutenberg University, Mainz, Germany. schneider@mpch-mainz.mpg.de"
Journal Title:		Environ Sci Technol
Year:		2005
Volume:		39
Issue:		16
Page Number:		6153 - 6161
DOI:		10.1021/es049427m
ISSN/ISBN:		0013-936X (Print) 0013-936X (Linking)
Abstract:		"Mass spectrometric measurements of size and composition of diesel exhaust particles have been performed under various conditions: chassis dynamometer tests, field measurements near a German motorway, and individual car chasing. Nucleation particles consisting of volatile sulfate and organic material could be detected both at the chassis dynamometer test facility and during individual car chasing. We found evidence that if nucleation occurs, sulfuric acid/water is the nucleating agent. Low-volatile organics species condense only on the preexisting sulfuric acid/water clusters. Nucleation was found to depend strongly on various parameters such as exhaust dilution conditions, fuel sulfur content, and engine load. The latter determines the fraction of the fuel sulfur that is converted to sulfuric acid. The organic compounds (volatile and low-volatile) condense only on preexisting particles, such as both sulfuric acid nucleation particles and larger accumulation mode soot particles. On the latter, sulfuric acid also condenses, if the conditions for nucleation are not given. The overall ratio of sulfate to organic (volatile and low-volatile) is also strongly dependent on the engine load. It was found that the production of nucleation particles even at high engine load can be suppressed by using low-sulfur fuel"
Keywords:		Air Pollutants/*analysis Carbon/analysis Environmental Monitoring/methods Mass Spectrometry Particle Size Vehicle Emissions/*analysis;
Notes:		"MedlineSchneider, J Hock, N Weimer, S Borrmann, S Kirchner, U Vogt, R Scheer, V eng 2005/09/22 Environ Sci Technol. 2005 Aug 15; 39(16):6153-61. doi: 10.1021/es049427m"