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This dataset and the methods used to obtain it were described in "Extreme molecular complexity resulting in a continuum of carbonaceous species in biomass burning tar balls from wildfire smoke" submitted to ACS Earth and Space Chemistry in May of 2021. Briefly, two samples of ambient aerosol were collected in the Pacific Northwest of the United States in 2017 which were heavily influenced by atmospheric tar balls. The acetonitrile soluble extracts of the aerosol filters were analyzed using ultrahigh resolution Orbitrap mass spectrometry (OTE-MS) using positive and negative modes of electrospray ionization as well as atmospheric pressure photoionization, for a total of four ionization modes. Data was collected for 200 scans over the range of m/z 100 to 800 and at a resolution of 240,000 (defined at m/z 400) with spectrum averaging. Mass lists were generated from an average of the 200 scans using Xcalibur software (Thermo Scientific v. 3.0). The newly developed MFAssignR (Schum et al. 2020) was used to estimate the noise threshold, recalibrate the spectra and assign molecular formulas to the measured masses. A series of custom R scripts (R v. 3.5.1 and RStudio v. 1.1.463) were used to perform blank subtraction and authenticate data quality. The resulting molecular formula assignments were reviewed for their credibility with respect to: oxygen to carbon ratio (O/C), hydrogen to carbon ratio (H/C), double bond equivalents (DBE), and absolute PPM mass error. The assigned molecular formulas were also analyzed using DBE and oxygen number trends as described by Herzsprung et al. (2014) and the unreliable formula assignments were removed. The glass transition temperature of the assigned molecular formulas were estimated using the model described in DeRieux et al. 2018. The saturation mass concentration of the assigned molecular formulas were estimated using the model described in Li et al. 2016.


Schum, S. K., Brown, L. E., and Mazzoleni, L. R., MFAssignR: Molecular formula assignment software for ultrahigh resolution mass spectrometry analysis of environmental complex mixtures, Environmental Research, 191, 110114, 2020.

Herzsprung, P., Hertkorn, N., von Tumpling, W., Harir, M., Friese, K., and Schmitt-Kopplin, P., Understanding molecular formula assignment of Fourier transform ion cyclotron resonance mass spectrometry data of natural organic matter from a chemical point of view, Anal Bioanal Chem, 406, 7977-7987, 2014.

DeRieux, W. S., Li, Y., Lin, P., Laskin, J., Laskin, A., Bertram, A. K., Nizkorodov, S. A., and Shiraiwa, M., Predicting the glass transition temperature and viscosity of secondary organic material using molecular composition. Atmos Chem Phys, 18 (9), 6331-6351, 2018.

Li, Y., Poschl, U., and Shiraiwa, M., Molecular corridors and parameterizations of volatility in the chemical evolution of organic aerosols. Atmos Chem Phys, 16 (5), 3327-3344, 2016.