Periodic intensity variations in the measured Compton profile anisotropies of ordinary ice Ih correspond to distances of 1.72 and 2.85 Å, which are close to the hydrogen bond length and the nearestneighbor O-O distance, respectively. We interpret this result as direct evidence for the substantial covalent nature of the hydrogen bond. Very good quantitative agreement between the data and a fully quantum mechanical bonding model for ice Ih and the disagreement with a purely electrostatic (classical) bonding model support this interpretation and demonstrate how exquisitely sensitive Compton scattering is to the phase of the electronic wave function. [S0031-9007(98)08227-1]

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We report the continuous variation of the spin moment of cobalt in LaCoO3 across its temperature and pressure-induced spin transitions evidenced with Kβ emission spectra. The first thermal transition is best described by a transition to an orbitally nondegenerate intermediate spin (S=1) state. In parallel, continuous redistribution of the 3d electrons is also indicated by partial fluorescence yield X-ray absorption spectra. At high pressure, our study confirms that the material becomes low spin between 40 and 70 kbar at room temperature.

We fabricated a graphene/few-layer InSe heterostructure photo-detector and solved a recurrent materials problem concerning degradation of ultra-thin atomic layers in air. This heterostructure has a largely enhanced performance explained by its fundamentally different mode of functioning with respect to the corresponding device without graphene.