• Electronic structure changes of highly dipolar and asymmetric merocyanine(HB238) has been investigated with UPS during growth. • Au, Ag and Cu(100) surfaces has been used to investigate chemical interaction between substrate and molecule at the monolayer regime. • Thickness dependent XPS measurements reveals the heteroatoms binding on various surfaces. • Influence of monolayer formation on molecular growth has been discussed. The growth and ordering of molecules on surfaces is an intriguing research topic as insights gained here can be of significant relevance for organic electronic devices. While often simple, rigid molecules are employed as model systems, we show results for a highly dipolar merocyanine which is studied on top of Au(100), Ag(100) and Cu(100) metal single crystals. Film thicknesses ranging from sub-monolayer to multilayer regimes are analyzed using UV (UPS) and X-ray photoelectron spectroscopy (XPS). For the monolayer regime, there is strong indication of face-on orientation, with both of the molecules’ sulfur atoms bonding to the metal surfaces. Here, on Ag and Au(100) the sulfur atoms lose some or all of their intrinsic charges due to a charge transfer with the substrate, while on Cu(100) a strong metal-sulfur bond forms. The interaction between the substrate and the molecules can also be seen in the intensity and width of the highest occupied molecular orbital features in UPS. Upon multilayer deposition, a gradual lowering in ionization energy is observed, likely due to the formation of antiparallel dimers followed by an increased charge carrier delocalization due to the formation of an extended molecular aggregate for thicker layers. Interestingly, on Cu(100) the aggregated phase is already observed for much lower deposition, showing the importance of substrate-molecule interaction on the subsequent film growth. Therefore, this study offers a detailed understanding of the interface formation and electronic structure evolution for merocyanine films on different metal surfaces.

Ammonia (NH3) dissociates efficiently when it interacts with an electron beam. This applies not only to single electron-NH3 collisions in the gas phase but also to electron irradiation of NH3 adsorbed on surfaces. The dissociation products include atomic hydrogen which can act as a reducing agent or NH2 radicals that can bind to suitable surfaces or to adsorbed molecules. This chemistry can be exploited in nanofabrication processes that use electron beams for deposition, etching, or modification of materials. This review describes the current state of insight regarding electron-induced reactions of NH3 adsorbed on surfaces and outlines approaches to the use of these reactions for enhancing electron beam induced nanofabrication processes. First, an overview of surface science studies on electron-induced reactions of NH3 adsorbed on single crystal surfaces is given. This is followed by a summary of studies on the use of NH3 for improving the purity of deposits prepared by electron beam induced deposition (EBID) and on the prospects of NH3 to suppress unwanted thermal surface chemistry during EBID. Finally, we discuss electron-induced reactions of NH3 that are fundamental to the modification of carbonaceous nanomaterials as well as potential application scenarios such as the functionalization of self-assembled monolayers and humidity sensing.

In this report we describe new findings on the structure, composition and thermal stability of FexNi1−x nanoparticles, synthesized via a magnetron sputtering source and deposited on a clean W(110) surface. The elemental distribution of the nanoparticles was determined by energy dispersive X-ray (EDX) and electron energy loss spectroscopy (EELS). The melting behavior of the nanoparticles was studied under UHV by scanning tunneling microscopy (STM) upon heating. Notably, it has been observed that the nanoparticle’s core is characterized by an enrichment of Ni atoms, while the shell shows a higher amount of Fe atoms. Specifically, in the case of Fe0.75Ni0.25 and Fe0.25Ni0.75, where a Ni core is surrounded by a Fe shell, all nanoparticles completely liquefy after heating at 540 K. In contrast, the Fe0.50Ni0.50 nanoparticles, which exhibit a homogeneous distribution of both elements, only begin to melt around 540 K.