Analysis of C, N and O in aerosol collected on an organic backing using internal blank measurements and variable beam size
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A method with low MDL (minimum detection limit) was developed for analysis of carbon (C), nitrogen (N) and oxygen (O) in aerosol samples collected on an organic backing. An accelerator-produced beam of protons interacting with the sample and the detection of elastically scattered protons (PESA; particle elastic scattering analysis) and emitted X-rays (PIXE; particle-induced X-ray emission) were the basic components of the setup. The method is based on measurement of internal blank concentrations, i.e. measurement of the blank concentration outside the aerosol deposit in each sample, and the use of two sizes of the beam in order to improve the MDL of the analysis. Large beam size covering the entire aerosol deposit was used to obtain quantitative analysis with PIXE. Small beam was used to obtain relative elemental concentrations with PESA and PIXE, which were transformed to absolute values by the aid of large-beam analysis. The small-size-beam served two purposes: to make internal blank measurements feasible and to improve the signal ratio of aerosol-deposit to backing. Compared with the traditional way of analysis, using a beam that is larger than the deposit and specially prepared blank samples, the new method reduced the MDL of C, N and O by a factor of 130, 70 and 90, respectively. The new method was applied to aerosol samples collected in the upper troposphere and the lowermost stratosphere from the CARIBIC platform. As far as the authors know, these measurements are the first quantitative determinations of C, N and O in the aerosol of this part of the atmosphere. The results show that these elements together with sulfur are major components of the aerosol. (C) 2007 Elsevier B.V. All rights reserved.
|Enheter & grupper|
Ämnesklassifikation (UKÄ) – OBLIGATORISK
|Tidskrift||Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms|
|Status||Published - 2007|
|Peer review utförd||Ja|