Models for chemical mechanisms of hydrocarbon oxidation rely on spectrometric identification of molecular structures in flames. Carbonyl (keto) compounds are well-established combustion intermediates. However, their less-stable enol tautomers, bearing OH groups adjacent to carbon-carbon double bonds, are not included in standard models. We observed substantial quantities of two-, three-, and four-carbon enols by photoionization mass spectrometry of flames burning representative compounds from modern fuel blends. Concentration profiles demonstrate that enol flame chemistry cannot be accounted for purely by keto-enol tautomerization. Currently accepted hydrocarbon oxidation mechanisms will likely require revision to explain the formation and reactivity of these unexpected compounds.

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In an atomically thin-film/dielectric-substrate heterostructure, the elemental physical properties of the atomically thin-film are influenced by the interaction between the thin-film and the substrate. In this article, utilizing monolayer MoS(2) on LaAlO(3) and SrTiO(3) substrates, as well as SiO2 and Gel-film as reference substrates similar to previously reported work [Nano Res, 2014, 7, 561], we systematically investigate the substrate effect on the photoluminescence of monolayer MoS(2). We observed significantly substrate-dependant photoluminescence of monolayer MoS(2), originating from substrate-to-film charge transfer. We found that SiO2 substrate introduces the most charge doping while SrTiO(3) introduces less charge transfer. Through the selection of desired substrate, we are able to induce different amounts of charge into the monolayer MoS(2), which consequently modifies the neutral exciton and charged exciton (trion) emissions. Finally, we proposed a band-diagram model to elucidate the relation between charge transfer and the substrate Fermi level and work function. Our work demonstrates that the substrate charge transfer exerts a strong influence on the monolayer MoS(2) photoluminescence property, which should be considered during device design and application. The work also provides a possible route to modify the thin-film photoluminescence property via substrate engineering for future device design.