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Growth of ordered perylene thin films on the Ag(110) surface has been investigated with scanning tunneling microscope. By saturating the surface with a monolayer of perylene molecules, two kinds of ordered structures are simultaneously formed with flat-lying perylene molecules on the Ag(110) surface, in which one is commensurate relative to the Ag substrate with a periodicity of (Multiple line equation(s) cannot be represented in ASCII text) while the other is commensurate with a periodicity of (Multiple line equation(s) cannot be represented in ASCII text). There is one molecule within the former unit cell with a surface coverage of 0.1 molecule per Ag atom, while there are two molecules within the latter unit cell, which gives a slightly lower surface coverage of 0.091 molecule per Ag atom. Ab initio calculations have been carried out to identify the adsorption geometry and bonding sites. [ABSTRACT FROM AUTHOR]

The structure of perylene adsorbed on Ru(0001) surface has been studied by ultraviolet photoemission spectroscopy (UPS) and low-energy electron diffraction. An ordered p(4×4) structure is observed from a monolayer (about 4 Å thickness) of the perylene on Ru(0001) surface. UPS measurements show the molecular features, from the perylene multiplayer, between 2 and 10 eV below the Fermi level. Angle-resolved ultraviolet photoemission spectroscopy measurements suggest that the perylene molecular plane is parallel to the substrate. Temperature dependent UPS measurements show that the perylene multilayer is stable on Ru(0001) surface up to 125 °C. The desorption of the multilayer and the decomposition of the monolayer are observed above 125 °C. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

K3C60, single crystal film was prepared on the cleaved (111) surface of C60, single crystal. Synchrotron radiation angle-resolved photoemission spectra were measured at normal emission with sample temperature at × 150K. Up to four subpeaks of LUMO-derived band were observed. These sub-peaks exhibit distinct energy dispersions which resemble in general the theoretical ones calculated for K3C60 at low temperature with the so-called one-dimensional disordered structure. But there is large deviation of experimental sub-band intervals from the theoretical values. This result is meaningful for the studies of the physical properties of alkali-doped C60 solids, e.g. the mechanism for superconductivity. [ABSTRACT FROM AUTHOR]

Self-assembled strategy has been proven to be a promising vista in constructing organized low-dimensional nanostructures with molecular precision and versatile functionalities on solid surfaces. Herein, we investigate by a combination of scanning tunneling microscopy (STM) and dispersion-corrected density functional theory (DFT), the adsorption of tetracene molecules on the silver substrate and the mechanism mediating the self-assembly on Ag(110). As expected, ordered domain is formed on Ag(110) after adsorption with adjacent molecules being imaged with alternating bright or dim pattern regularly. While such behavior has been assigned previously to the difference of molecular adsorption height, herein, it is possible to investigate essentially the mechanism leading to the periodic alternation of brightness and dimness for tetracene adsorbed on Ag(110) thanks to the consideration of Van der Waals (vdW) dispersion force. It is demonstrated that the adsorption height in fact is same for both bright and dim molecules, while the adsorption site and the corresponding interfacial charge transfer play an important role in the formation of such pattern. Our report reveals that vdW dispersion interaction is crucial to appropriately describe the adsorption of tetracene on the silver substrate, and the formation of delicate molecular architectures on metal surfaces might also offers a promising approach towards molecular electronics. [ABSTRACT FROM AUTHOR]

Synchrotron radiation angle resolved photoemission spectra (PES) were measured on the (111) surface of K3C60 single crystal film at three different temperatures, namely, 190, 220 and 300 K. Dispersions for the subbands of the conduction band along the [111] direction could be observed clearly at 190 K, and the band structure was nearly the same as that at 150 K corresponding to the one-dimensional-disordered orientational structure (1DDS) of K3C60. Most subpeaks smeared and the dispersions could no longer be observed when the sample temperature was raised to 220 K. The PES at room temperature differed remarkably from that at lower temperatures. The change of spectra with temperature is consistent with an orientational phase transition at 200 K, and can be explained by the theory of the fcc antiferromagnetic Ising model, assuming that the 1DD structure at lower temperatures converts to be a mixture of bi-directional structure domains and disordered molecules at higher temperatures. [Copyright &y& Elsevier]

Abstract: The growth of tetracene on SiO2/Si(111) substrate has been studied by ultraviolet photoemission spectroscopy measurements. Seven emission features of the organic material are located at 2.26, 3.56, 4.77, 5.88, 6.98, 8.18 and 9.90eV, respectively, below the Fermi level. The changes in binding energy and work function during the deposition of tetracene molecules on SiO2 substrate indicate an interaction between tetracene molecule and substrate. The interaction between tetracene molecule and substrate is weaker than that between the organic and silicon substrate. The reduction in work function is due to the formation of interface dipole. Based on the density functional theory (DFT) calculation, tetracene molecules are arranged in an upright standing manner with the optimal growth of a small cluster consisting four molecules. [Copyright &y& Elsevier]

Examines the growth of centimeter-sized carbon[sub 60] through vapor method by nucleation control. Administration of the process through proper time-dependent temperature; Observation of the sample using x-ray diffraction pattern; Investigation of the fine structure of valence bonds of the crystal.