We dissolved 1-iodo-4-nitrobenzene in various solvents, including ethanol, benzene, toluene and dimethylacetamide, and prepared solution with different concentration from 10-2 M to 10-5 M. Epitaxial Au(111) film and graphite were used as substrates. Scanning tunneling microscope (STM) was used to observe structures of 1-iodo-4-nitrobenzene molecules on those substrates. Experimentally, we found that 1-iodo-4-nitrobenzene molecules constructed nanowires on graphite surface at room temperature in air. The mechanism of formation of nanowire is briefly discussed in this paper.

Highly conductive and transparent indium tin oxide (ITO) thin films, each with a thickness of 100 nm, were deposited on glass and Si(100) by direct current (DC) magnetron sputtering under an argon (Ar) atmosphere using an ITO target composed of 95% indium oxide and 5% tin oxide for photon-STM use. X-ray diffraction, STM observations, resistivity and transmission measurements were carried out to study the formation of the films at substrate temperatures between 40 and 400 ◦C and the effects of thermal annealing in air between 200 and 400 ◦C for between 1 and 5 h. The film properties were highly dependent on deposition conditions and on post-deposition film treatment. The films deposited under an Ar atmosphere pressure of 1.7×10−3 Torr by DC power sputtering (100W) at substrate temperatures between 40 and 400 ◦C exhibited resistivities in the range 3.0–5.7×10−5 Ωm and transmissions in the range 71%–79%. After deposition and annealing in air at 300◦C for 1 h, the films showed resistivities in the range 2.9–4.0×10−5 Ωm and transmissions in the range 78%–81%. Resistivity and transmission measurements showed that in order to improve conductive and transparent properties, 2 h annealing in air at 300 ◦C was necessary. X-ray diffraction data supported the experimental measurements of resistivity and transmission on the studies of annealing time. The surface roughness and film uniformity improve with increasing substrate temperature. STM observations found the ITO films deposited at a substrate temperature of 325 ◦C, and up to 400 ◦C, had domains with crystalline structures. After deposition and annealing in air at 300 ◦C for 1 h the films still exhibited similar domains. However, after deposition at substrate temperatures from 40 ◦C to 300 ◦C, and annealing in air at 300◦C for 1 h, the films were shown to be amorphous. More importantly, the STM studies found that the ITO film surfaces were most likely to break after deposition at a substrate temperature of 325 ◦C and annealing in air at 300◦C for 2 or 3 h. Such findings give some inspiration to us in interpreting the effects of annealing on the improvement of conductive and transparent properties and on the transition of phases. In addition, correlations between the conductive/transparent properties and the phase transition, the annealing time and the phase transition, and the conductive/transparent properties and the annealing time have been investigated.

Orbital-mediated tunneling spectra obtained in the STM environment are reported for nickel(II) tetra-phenylporphyrin, NiTPP, as a function of molecule-tip separation. Spectra were acquired over a range of tip motion of 0.42 nm. Spectra did not show the variation in band splitting with tip distance predicted by several models. It appears for molecules such as NiTPP that the average potential at the molecule is essentially the same as at the metal substrate, at least for gap resistance values greater than 500 M

An ultrahigh-vacuum scanning tunneling microscopy equipped with a conductive optical fiber tip and photon detector has been established to explore photon emission from a self-assembled monolayer (SAM) of Cu-tetra-[3,5-di-t-butylphenyl] porphyrin (Cu-TBPP) molecules on a Cu(100) surface. In a few nanometer scale areas, emitted photons from molecules induced by tunneling electrons were effectively collected within the near-field region through an apex of the conductive optical fiber tip. The photon emission can be attributed to the inelastic tunneling involving the optical fiber tip, the Cu-TBPP molecules, and the Cu~100! surface. We proposed two kinds of mechanisms in terms of the photon emission from a SAM of Cu-TBPP molecules on a Cu(100) surface. The quantum efficiency for molecular fluorescence induced by inelastic tunneling can be approximately estimated to be ;3.031026 photons per electron in the current experimental studies.

Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) ere performed on monolayer film of NiTPP supported on Au(111) under ultrahigh vacuum (UHV) conditions. The constant current STM images show remarkable bias dependence. High resolution STM data clearly show the individual NiTPP molecules and allow easy differentiation between NiTPP and CoTPP reported before. Scanning tunneling spectra, as a function of molecule-tip separation, were acquired over a range of tip motion of 0.42 nm. Spectra do not show the variation in band splitting with tip distance. It appears for molecules such as NiTPP that the average potential at the molecule is essentially the same at the same metal substrate. For molecules of the height of NiTPP, the scanning tunneling spectra should give reliable occupied and unoccupied orbital energies over a wide range of tipmolecule distances.