Nanohybrids of 2D Black Phosphorus with Phthalocyanines: Role of Interfacial Interactions in Heterostructure Development.

New 2D black phosphorus (bP)-phthalocyanine (Pc) nanohybrids have been synthesized by liquid phase exfoliation of black phosphorus crystals in the presence of two organic dyes: phthalocyanine (Pc) and manganese phthalocyanine (MnPc). The key role of the metal cation in the interfacial interaction between the organic dye and bP nanosheets was demonstrated by X-ray absorption spectroscopy and associated with an electron transfer between the metal cation Mn and bP nanosheets, which resembles a coordinative chemical bond. On the other hand, the interaction between bP nanosheets and pure phthalocyanine is governed by van der Waals forces.

Oxygen-Promoted on-Surface Synthesis of Polyboroxine Molecules.

We present a protocol for the on-surface synthesis of polyboroxine molecules derived from boroxine molecules precursors. This process is promoted by oxygen species present on the Au(111) surface: oxygen atoms facilitate the detachment of naphthalene units of trinaphthyl-boroxine molecules and bridge two unsaturated boroxine centers to form a boroxine-O-boroxine chemical motif. X-ray spectroscopic characterization shows that, as the synthesis process proceeds, it progressively tunes the electronic properties of the interface, thus providing a promising route to control the electron level alignment.

Atom-Specific Probing of Electron Dynamics in an Atomic Adsorbate by Time-Resolved X-Ray Spectroscopy.

The electronic excitation occurring on adsorbates at ultrafast timescales from optical lasers that initiate surface chemical reactions is still an open question. Here, we report the ultrafast temporal evolution of x-ray absorption spectroscopy (XAS) and x-ray emission spectroscopy (XES) of a simple well-known adsorbate prototype system, namely carbon (C) atoms adsorbed on a nickel [Ni(100)] surface, following intense laser optical pumping at 400 nm. We observe ultrafast (∼100  fs) changes in both XAS and XES showing clear signatures of the formation of a hot electron-hole pair distribution on the adsorbate.

Symmetry-resolved CO desorption and oxidation dynamics on O/Ru(0001) probed at the C K-edge by ultrafast x-ray spectroscopy.

We report on carbon monoxide desorption and oxidation induced by 400 nm femtosecond laser excitation on the O/Ru(0001) surface probed by time-resolved x-ray absorption spectroscopy (TR-XAS) at the carbon K-edge. The experiments were performed under constant background pressures of CO (6 × 10 Torr) and O (3 × 10 Torr). Under these conditions, we detect two transient CO species with narrow 2π* peaks, suggesting little 2π* interaction with the surface.