Single‐particle mass spectrometry of tropospheric aerosol particles

The Particle Analysis by Laser Mass Spectrometry (PALMS) instrument has measured the composition of single particles during a number of airborne and ground‐based campaigns. In the regions studied, 30% to over 80% of the aerosol mass in the free troposphere was carbonaceous material. Most of this carbonaceous material was probably organic. Although there were variations in their amounts, over 90% of accumulation mode particles away from local sources were internal mixtures of sulfates and carbonaceous material. Within this internal mixing, there was variation in the pattern of carbonaceous peaks in the spectra, especially in peaks related to organic acids. Particles with a biomass burning signature were a…