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aircraft exhaust; positive and negative chemiions; aerosol formation; mass spectrometry
Abstract:
Mass distributions of positive and negative chemiions (CI) were measured in the exhaust plume of an aircraft jet engine at the ground at exhaust gas ages around 0.1 s using an ion mass spectrometer with a mass range of 8500 amu (large ion mass spectrometer, LIOMAS). Most of the CI had mass numbers m < 2000, but very massive CI with m up to at least 8500 were also observed. About 1% of the negative CI and 0.2% of the positive CI had in > 8500. An increase of the fuel sulfur content from 2 to 66 mg/kg did not change the ion mass distributions. This indicates that most of the observed CI did not contain sulfur- bearing molecules, but probably contained low volatility organic compounds (LVOC). An LVOC-emission index of 22.5 mg LVOC/kg fuel is inferred from our data. (C) 2002 Elsevier Science Ltd. All rights reserved.
