Particulate emissions from jet aircraft are a significant source of carbonaceous particles in the troposphere and lower stratosphere. Determining their physical structure and chemistry is relevant to assess their impact upon contrail formation, the radiative balance of the atmosphere, and human health. In this report, aircraft soot particles emitted by a recent turbofan engine, the PowerJet SaM146-1S17, fueled with Jet A-1, have been investigated with high-resolution transmission electron microscopy-in imaging, selected area electron diffraction mode, and energy dispersive X-ray spectroscopy-, Raman spectroscopy, X-ray photoelectron spectroscopy and near-edge X-ray absorption spectroscopy. This set of complementary techniques provides detailed structural and chemical information of the surface and the bulk of soot primary particles. Independently of the engine operating regimes, these particles are mainly composed of graphitic layers arranged in onion-like, turbostratic structures. They are poorly oxidized, with a slight enhancement of the oxidation rate at the very surface. The soot's surface also presents a high concentration of unsaturated organic hydrocarbons and structural defects. These results allow a better description of aircraft soot at the atomic level, and may account for a better understanding of ice nucleation in aircraft contrails formation.

The fundamental electronic structure of the widely used battery material Li(x)CoO(2) still remains a mystery. Soft x-ray absorption spectroscopy of Li(x)CoO(2) reveals that holes with strong O 2p character play an essential role in the electronic conductivity of the Co(3+)/Co(4+) mixed valence CoO(2) layer. The oxygen holes are bound to the Co(4+) sites and the Li-ion vacancy, suggesting that the Li-ion flow can be stabilized by oxygen hole back flow. Such an oxygen hole state of Li(x)CoO(2) is unique among the various oxide-based battery materials and is one of the key ingredients to improving their electronic and Li-ion conductivities.

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