Secondary organic aerosol explained

A secondary organic aerosol (SOA) is a molecule produced via oxidation over several generations of a parent organic molecule.^[1] In contrast to primary organic aerosols, which are emitted directly from the biosphere, SOAs are either formed via homogeneous nucleation through the successive oxidation of gas-phase organic compounds, or through condensation on pre-existing particles. These gas-phase species exert high vapor pressures, meaning they are volatile and stable in the gas-phase.

Upon oxidation, the increased polarity, and thus reduced volatility, of the molecules results in a reduction of vapor pressure. After sufficient oxidation, the vapor pressure is sufficiently low that the gas-phase compound partitions into the solid-phase, producing secondary organic matter (the particle phase of SOA).

SOAs represent a significant proportion of aerosols contained in the troposphere.^[1]

References

Bibliography

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Notes and References

1. Secondary Organic Aerosol Formation from Low-NOx Photooxidation of Dodecane: Evolution of Multigeneration Gas-Phase Chemistry and Aerosol Composition. The Journal of Physical Chemistry A. 2012-06-21. 1089-5639. 6211–6230. 116. 24. 10.1021/jp211531h. 22424261. Lindsay D.. Yee. Jill S.. Craven. Christine L.. Loza. Katherine A.. Schilling. Nga Lee. Ng. Manjula R.. Canagaratna. Paul J.. Ziemann. Richard C.. Flagan. John H.. Seinfeld. 2012JPCA..116.6211Y. 24782263 .