Chemical ionization mass spectrometry with the nitrate reagent ion (NO- 3 CIMS) was used to investigate the products of the nitrate radical (NO3) initiated oxidation of four monoterpenes in laboratory chamber experiments. a-Pinene, b-pinene, d-3-carene, and a-thujene were studied. The major gas-phase species produced in each system were distinctly different, showing the effect of monoterpene structure on the oxidation mechanism and further elucidating the contributions of these species to particle formation and growth. By comparing groupings of products based on the ratios of elements in the general formula CwHxNyOz, the relative importance of specific mechanistic pathways (fragmentation, termination, and radical rearrangement) can be assessed for each system. Additionally, the measured time series of the highly oxidized reaction products provide
insights into the ratio of relative production and loss rates of the high-molecular-weight products of the d-3-carene system. The measured effective O:C ratios of reaction products were anticorrelated with new particle formation intensity and number concentration for each system; however, the monomer : dimer ratios of products had a small positive trend. Gas-phase yields of oxidation products measured by nitrate CIMS correlated with particle number concentrations for each monoterpene system, with the exception of α-thujene, which produced a considerable amount of low-volatility products but no particles. Species-resolved wall loss was measured with nitrate CIMS and found to be highly variable among oxidized reaction products in our stainless steel chamber.

The interested reader is referred to the following article for details about the experiments performed here:

Dam, M., Draper, D. C., Marsavin, A., Fry, J. L. and Smith, J. N.: Observations of gas-phase products from the nitrate radical-initiated oxidation of four monoterpenes, Atmos. Chem. Phys., 2022, 1–22, doi:10.5194/acp-2021-1020, 2022.

These tables contained processed data that are plotted and tabulated in the manuscript referred to above. All experiments numbers in these tables refer to those described in the article. Data format is comma-delimited ASCII. 

Additional questions and requests for other processed data associated with the article can be directed to James Smith (jimsmith@uci.edu).