Impacts of Aerosol Aging on Laser Desorption/Ionization in Single-Particle Mass Spectrometers

Figures & data

FIG. 1. (a) Number fraction of particle classes at each thermodenuder temperature. The black trace represents the fraction of hit particles: hit/(hit+missed). The standard error of the hit% ranges from 0.2% (unheated) to 0.8% (230°C). (b) Average mass spectrum of unheated organic carbon particles.

FIG. 2. Thermograms for several aerosol constituents for the AMS bulk aerosol data, compared to those derived from the different peak area metrics for ATOFMS data. The ATOFMS peak area metrics are: APA = absolute peak area; RPA = relative peak area; RC = reference component. The ATOFMS ion peaks are: (a) sulfate, m/z −97 (HSO₄⁻); (b) nitrate, m/z −62 (NO₃⁻); (c) ammonium, m/z 18 (NH₄⁺); (d) amines, m/z 86 ((C₂H₅)₂NCH₂⁺); and (e) organic carbon marker m/z 27 (C₂H₃⁺). Also shown in panel (e) are m/z 37 (C₃H⁺, dark grey, dashed line) and, m/z 43 (C₂H₃O⁺, light grey, dashed line), both calculated via the RC method. The AMS curve in panel (e) represents total organic aerosol. Panel (f) displays the thermograms of total negative and positive ion intensities and the fraction of C₃⁺ (m/z 36), used as the reference component for the OC type. Error bars for ATOFMS data represent 95% confidence intervals and may be hidden by the data marker.

FIG. 3. Mass spectral subtraction plot of the average mass spectrum corresponding to OC particles at 83°C minus unheated OC particles. Positive intensity peaks correspond to higher abundance in the 83°C particles, whereas negative intensity peaks show higher intensity in the unheated particles.