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An investigation on the growth behavior of FePc on a Ag (110) surface is carried out by using scanning tunneling microscopy (STM). At an FePc coverage of 3.5 ML, an ordered superstructure (densely packed) with a lateral shift is observed. The densely packed superstructure can be attributed to the substrate commensuration and the intermolecular van der Waals attractive interaction. The in-plane lateral shift in the superphase is specifically along the direction of [10] azimuth. The results provide a new perspective to understanding the intermolecular and the molecule—substrate interactions.

Using scanning tunneling microscopy (STM) together with density functional theory (DFT) the growth behavior of perylene on the Cu(100) substrate has been investigated. As revealed by STM images, perylene molecules prefer to adopt lying configuration with their molecular plane parallel to the substrate, and two symmetrically equivalent ordered domains were observed. DFT calculations show that perylene molecule prefers to adsorb on the top site of substrate Cu atoms with its long molecular axis aligning along the [011] or [01-1] azimuth of the substrate which is the most stable adsorption geometry according to its highest binding energy. Consequently, two adsorption structures of c(8×4) and c(8×6), each containing two perylene molecules per unit cell, are proposed based on our STM images. The growth mechanism for ordered perylene domains on Cu(100) can be attributed to the balance between weak adsorbate-adsorbate interaction and comparable adsorbate-substrate interaction.

The interfacial electronic states of tetracene on Si(111) 7×7 substrate were studied by using ultraviolet photoelectron spectroscopy (UPS). After deposition of tetracene on the Si(111) 7×7 surface, the features originating from the tetracene molecule appear at 1.55, 3.36, 6.78, 9.24, and 10.76 eV below the Fermi level; they shift in binding energy with increasing organic film coverage. From the UPS measurements, the work function of the sample surface was found to decrease with increasing molecular coverage in the submonolayer range suggesting that an interfacial dipole is formed. A density functional theory calculation had also been carried out to determine the favorable adsorption structure. The molecule near the top of a center adatom with the longer molecular axis along the [11¯0] azimuth is the most favorable.

Lattice-matched PbTe/CdTe(111) heterojunction interfaces were studied using x-ray photoelectron spectroscopy. A type-I band alignment with a valence band offset of ΔEV=0.135±0.05 eV and a conduction band offset of ΔEC=1.145±0.05 eV is concluded. Within experimental error the determined valence band offset is in agreement with theoretical prediction by inclusion of spin-orbit interaction.

The ordered adsorption structures of tetracene on Ag(110) have been studied by low energy electron diffraction (LEED), scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. At a low coverage, as calibrated with LEED, both p(4 x 4) and c(8 x 4) ordered structures are simultaneously formed on an Ag(110) surface at room temperature. STM images suggest the molecular plane is parallel to the Ag surface with its long molecular axis aligned along the [001] azimuth. DFT optimization reveals a separation of 0.3 nm between the molecular plane and substrate surface while the center of the tetracene molecule is on the long bridge site. Increasing coverage slightly, a structure is formed while the adsorbed molecules maintain the flat-lying geometry with adjacent molecules alternating their height relative to the surface.

The geometrical arrangement of tetracene on Cu (100) surface at monolayer coverage is studied by using scanning tunneling microscopy measurement and density functional theory (DFT) calculations. Tetracene molecule is found to be oriented with its molecular plane parallel to the substrate surface, and no perpendicular geometry is observed at this coverage. The molecule is aligned either in the [011] or [011¯] direction due to the fourfold symmetry of the Cu (100) surface. DFT calculations show that the molecule with the “flat-lying” mode has larger adsorption energy than that with the “upright standing” mode, indicating that the former is the more stable structure. With the flat-lying geometry, the carbon atoms prefer to be placed between surface Cu atoms. The molecular center prefers to be located at the bridge site between two nearest surface Cu atoms.

We performed investigations on the formation of Ag∕PbTe(111) interface by using photoemission spectroscopy. Upon initial Ag deposition, both Pb 4f and Te 3d core levels and the valence-band edge showed shifts to high binding energy, from which the band bending at Ag∕PbTe(111) is determined to be 0.13eV. Upon further Ag deposition, new components appear in Pb and Te core levels, with intensities remaining constant even at higher Ag thickness. The experimental results, together with ab initio calculation, indicate that both Te and Pb outdiffuse to the outmost surface, and a single Te-terminated Pb–Te bilayer is formed over Ag film on PbTe(111).

The electronic structure of tetracene on Cu (110) surface has been studied by using ultraviolet photoemission spectroscopy (UPS). The emission features from the organic molecule are located from 1 to 10 eV below the Fermi level, and they shift in binding energy with increasing the coverage of the organic material. For the surface with multilayer of tetracene, six well-resolved features were found at 1.90, 3.40, 4.70, 5.95, 6.95, and 9.15 eV below the Fermi level, respectively. On the surface with a lower coverage of tetracene, angle-resolved UPS measurements suggest that the molecular plane is parallel to the substrate. Density functional theory calculation confirms the flat-lying adsorption mode and shows that the tetracene molecule prefers to be adsorbed on the long bridge site with its long axis in the [1(1)over bar 0] azimuth.

Tetracene on the Ru( 10 (1) over bar0) surface has been investigated by ultraviolet photoemission spectroscopy ( UPS). The UPS results show features, from tetracene, between 2.0 and 10.0 eV below the Fermi level, and their shift in binding energy with increasing coverage. Angle-resolved UPS (ARUPS) results indicate that the molecular plane of tetracene near the interface is parallel to the substrate. Moreover, an ab initio calculation has also been carried out to determine the favourable adsorption structure. Temperature-dependent UPS measurements show that tetracene is stable on the Ru( 10 (1) over bar0) surface up to 150 degrees C.

Phonon modes of PbTe films grown by molecular beam epitaxy have been studied by micro-Raman scattering. On the as-grown PbTe surface, strong TeO2 phonon vibrational modes were detected, which obscured the observation of the longitudinal optical (LO) phonons of PbTe in early conventional Raman scattering experiments. Existence of a TeO2 layer on the PbTe surface is confirmed by observation with x-ray photoemission spectroscopy. After removal of TeO2 by chemical etching, the LO phonons for PbTe films were unambiguously observed. Misfit strain accommodated in the epitaxial films makes the lattice distorted from cubic structure, which lowers the crystal symmetry and leads to observation of what would normally be Raman inactive LO phonon modes for PbTe.

Copper phthalocyanines (CuPc) on a Ag(110) surface have been studied by ultraviolet photoemission spectroscopy (UPS). On depositing CuPc organic films, the features from the substrate 3d valence fade and four new features corresponding to the adsorbed molecules emerge at 1.68, 4.45, 6.36 and 9.20 eV below the Fermi level. These features shift in binding energy with increasing thickness of the organic films. In the case of a monolayer, angle-resolved UPS measurements suggest that the molecular plane is nearly parallel to the substrate. Further theoretical calculation indicates that the adsorption of CuPc on a hollow site is the most favourable configuration, and the separation between the adsorbate and the substrate is about 2.7 A.

Transportation of mass molecules from one metal surface to another has been achieved with scanning tunneling microscope tip at room temperature. With scanning monolayer of tetracene on Ag(110) surface, the molecules were removed gradually, leaving ordered stripes on the Ag surface; the ordered stripes are unidirectional nanoscopic molecular rows with a width of about 1.4nm. Scanning the clean Ru(101¯0) sample with the tip, previously adsorbed the tetracene molecules, caused an appearance of the molecules on the Ru surface. Short molecular strips with different widths from 4to20nm were drawn on the Ru surface by a molecule-loaded W tip.

The growth of epitaxial monolayer of perylene on Ru(0001) was investigated by means of scanning tunneling microscopy (STM). The STM images showed a coexistence of the ordered phase with a 12×12 superstructure and the disordered phase in a monolayer of perylene on Ru(0001). In the disordered region, the perylene molecules are randomly distributed, and orientated uniformly with their long axis in the [1000] direction. For the ordered phase, a model of the Ru(0001)-(12×12)-8 perylene superstructure was proposed. The results indicate that the growth behavior of perylene on Ru(0001) is mainly controlled by laterally repulsive molecule-molecule interaction.