Investigation of particle elastic scattering analysis as a complementary technique to pixe for aerosol characterization

Abstract

The possibility of analysis by the detection of elastically scattered particles for carbon, nitrogen, oxygen and also hydrogen determination in the fine mode of aerosols has been investigated. The main objectives in this study have been to find suitable projectiles (protons or alpha particles) and projectile energy, in order to obtain separated peaks for the elements of interest and to achieve high analytical sensitivity and precision. Sensitive PIXE analysis should also be obtained on an aerosol substrate suitable for both methods. Relative scattering cross sections at an angle of 170° for protons (3.5–5.8 MeV) and alpha particles (8–9 MeV) on 12C, 14N and 16O have been investigated. Lower and upper energy limits are set by the demand for resolved peaks from C, N and O and the accelerator available, respectively. Protons were found to be the most suitable projectiles and for one proton energy, 3.58 MeV, fulfilling the requirements mentioned above, the possibility for H determination at laboratory scattering angles between 29° and 59° has been investigated. Some aerosol filters and foils have also been investigated at this proton energy in order to find a suitable aerosol substrate. The lowest detection limits were obtained for thin aluminum foils, yielding 15, 10 and 350 ng cm −2 for C, N and O, respectively, and PIXE detection limits comparable to those obtained with a Nuclepore ® filter.