Alkynyl Linkers as a Design Tool to Gain Control over the Self-Assembly of Meso-Substituted Porphyrins on HOPG.

Self-assembled monolayers (SAMs) fall generally into two broad categories: those that are covalently bound either to the surface or to each other and those that rely on weaker forces such as hydrogen bonding or van der Waals forces. The engineering of the structure of SAMs formed from weaker forces is an exciting and complex field that often utilizes long alkane substituents bound to core moieties. The core provides the unique optical, electronic, or catalytic property desired, while the interdigitation of the alkane chains provides the means for creating well-regulated patterns of cores on the substrate.

Design, Synthesis, and Evaluation of CFAuCNR Precursors for Focused Electron Beam-Induced Deposition of Gold.

The Au(I) complexes CFAuCNMe (1a) and CFAuCN Bu (1b) were investigated as Au(I) precursors for focused electron beam-induced deposition (FEBID) of metallic gold. Both 1a and 1b are sufficiently volatile for sublimation at 125 ± 1 mTorr in the temperature range of roughly 40-50 °C. Electron impact mass spectra of 1a-b show gold-containing ions resulting from fragmenting the CF group and the CNR ligand, whereas in negative chemical ionization of 1a-b, the major fragment results from dealkylation of the CNR ligand.

Individually grown cobalt nanowires as magnetic force microscopy probes.

AC electric fields were utilized in the growth of individual high-aspect ratio cobalt nanowires from simple salt solutions using the Directed Electrochemical Nanowire Assembly method. Nanowire diameters were tuned from the submicron scale to 40 nm by adjusting the AC voltage frequency and the growth solution concentration. The structural properties of the nanowires, including shape and crystallinity, were identified using electron microscopy.

Electron induced surface reactions of (η-CH)Fe(CO)Mn(CO), a potential heterobimetallic precursor for focused electron beam induced deposition (FEBID).

Electron-induced surface reactions of (η-CH)Fe(CO)Mn(CO) were explored in situ under ultra-high vacuum conditions using X-ray photoelectron spectroscopy and mass spectrometry. The initial step involves electron-stimulated decomposition of adsorbed (η-CH)Fe(CO)Mn(CO) molecules, accompanied by the desorption of an average of five CO ligands. A comparison with recent gas phase studies suggests that this precursor decomposition step occurs by a dissociative ionization (DI) process.

Low energy electron-induced decomposition of (η-Cp)Fe(CO)Mn(CO), a potential bimetallic precursor for focused electron beam induced deposition of alloy structures.

The production of alloyed nanostructures presents a unique problem in focused electron beam induced deposition (FEBID). Deposition of such structures has historically involved the mixing of two or more precursor gases in situ or via multiple channel gas injection systems, thereby making the production of precise, reproducible alloy compositions difficult. Promising recent efforts to address this problem have involved the use of multi-centred, heterometallic FEBID precursor species.

Comparing postdeposition reactions of electrons and radicals with Pt nanostructures created by focused electron beam induced deposition.

The ability of electrons and atomic hydrogen (AH) to remove residual chlorine from PtCl deposits created from -Pt(CO)Cl by focused electron beam induced deposition (FEBID) is evaluated. Auger electron spectroscopy (AES) and energy-dispersive X-ray spectroscopy (EDS) measurements as well as thermodynamics calculations support the idea that electrons can remove chlorine from PtCl structures via an electron-stimulated desorption (ESD) process. It was found that the effectiveness of electrons to purify deposits greater than a few nanometers in height is compromised by the limited escape depth of the chloride ions generated in the purification step.

Photocatalytic Activity and Fluorescence of Gold/Zinc Oxide Nanoparticles Formed by Dithiol Linking.

Monolayer-protected gold nanoparticles (AuNPs) with average diameters of 2-4 nm have been covalently attached to zinc oxide nanorods using dithiol ligands. Electron microscopy and Raman spectroscopy show that ozone treatment or annealing at 300 or 450 °C increases the average diameter of the AuNPs to 6, 8, and 14 (±1) nm, respectively, and decomposes the organic layers to various degrees. These treatments locate the AuNPs closer to the nanorods.