Synchrotron plus Mass Spectrometer equals New Insights Into Combustion Chemistry

Unique analysis of the reaction of propene with oxygen atom reveals the influence of electron spin on combustion chemistry.

Image courtesy of Sandia National Laboratories
Photoionization/mass spectrometry apparatus at the Advanced Light Source.

The Science

The electron spin of oxygen atom’s lone unpaired electron in the oxidation of propene was revealed to influence the reaction in an unexpected direction. Using a new probe of gas-phase chemistry combining synchrotron-based photoionization with time-resolved mass spectrometry, unexpectedly large amounts of reaction products were identified from a reaction pathway predicted to be “spin-forbidden.”

The Impact

Synchrotron-based, tunable photoionization combined with mass spectrometry enables detailed studies of combustion reactions that provide critical validation of predictive models.


Researchers at the Combustion Research Facility, Sandia National Laboratories, have obtained detailed insights into the oxidation of hydrocarbons, the first step in combustion, by use of a new gas-phase chemistry probe that combines synchrotron-based photoionization with mass spectrometry. The simple oxygen atom is an important combustion reactant as an oxidizer of hydrocarbon fuels. But reactions of individual oxygen atoms with other molecules are challenging to understand because of the unpaired electron of oxygen. Conventional understanding says that flipping the oxygen electron’s spin in the course of a reaction is “forbidden.” Synchrotron studies of the reaction of oxygen atoms with propene, a representative unsaturated hydrocarbon, differentiated between spin-allowed versus forbidden pathways and revealed unexpectedly large amounts of spin-forbidden products. This work is providing remarkable new insights that will profoundly affect our ability to accurately simulate the complex chemistry of combustion processes.


David L. Osborn
Sandia National Laboratories


Office of Science Basic Energy Sciences (BES) program


J.D. Savee, et al., “New mechanistic insights to the O(3P) + propene reaction from multiplexed photoionization mass spectrometry,” Phys. Chem. Chem. Phys. 14 10410 (2012). [DOI: 10.1039/c2cp41200d]

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