Self-assembled monolayers (SAMs) of dipolar phosphonic acids can tailor the interface between organic semiconductors and transparent conductive oxides. When used in optoelectronic devices such as organic light emitting diodes and solar cells, these SAMs can increase current density and photovoltaic performance. The molecular ordering and conformation adopted by the SAMs determine properties such as work function and wettability at these critical interfaces. We combine angle-dependent near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) to determine the molecular orientations of a model phenylphosphonic acid on indium zinc oxide, and correlate the resulting values with density functional theory (DFT). We find that the SAMs are surprisingly well-oriented, with the phenyl ring adopting a well-defined tilt angle of 12-16° from the surface normal. We find quantitative agreement between the two experimental techniques and density functional theory calculations. These results not only provide a detailed picture of the molecular structure of a technologically important class of SAMs, but also resolve a long-standing ambiguity regarding the vibrational-mode assignments for phosphonic acids on oxide surfaces, thus improving the utility of PM-IRRAS for future studies.

A novel synthetic route to functionalize and magnetically assemble ferromagnetic colloids into one-dimensional (1-D) carbon nanostructures is reported. The synthesis of ferromagnetic cobalt nanoparticles with polyacrylonitrile (PAN) shells was achieved by ligand exchange of PAN onto preformed polystyrene-coated ferromagnetic cobalt nanoparticles. PAN-coated ferromagnetic nanoparticles (PAN-CoNPs) were then cast onto supporting surfaces from N,N-dimethylformamide (DMF) in the presence of an external magnetic field and pyrolyzed to form 1-D carbon nanoparticle chains spanning microns in length. Atomic force microscopy, field emission scanning electron microscopy, Raman spectroscopy, vibrating sample magnetometry, and X-ray diffraction were used to confirm the preparation of these 1-D hybrid nanostructures. This versatile methodology provides an alternative approach to prepare 1-D carbon materials using soluble precursors that can be magnetically directed and organized.

Thin films of solid-state benzene at 30 K were reacted with small quantities of vapor-deposited Ag, Mg, and Al under ultrahigh vacuum, and products were monitored using surface Raman spectroscopy. Although Ag and Mg produce small amounts of metalÀbenzene adduct products, the resulting Raman spectra are dominated by surface enhancement of the normal benzene modes from metallic nanoparticles suggesting rapid Ag or Mg metallization of the film. In contrast, large quantities of Al adduct products are observed. Vibrational modes of the products in all three systems suggest adducts that are formed through a pathway initiated by an electron transfer reaction. The difference in reactivity between these metals is ascribed to differences in ionization potential of the metal atoms; ionization potential values for Ag and Mg are similar but larger than that for Al. These studies demonstrate the importance of atomic parameters, such as ionization potential, in solid-state metalÀorganic reaction chemistry.