Making contact of transition metal dichalcogenides (TMDCs) with a metal surface is essential for fabricating and designing electronic devices and catalytic systems. It also generates strain in the TMDCs that plays significant role in both electronic and phonon structures. Therefore, detailed understanding of mechanism of the strain generation is important to fully comprehend the modulation effect for the electronic and phonon properties. Here, MoS and MoSe monolayers are grown on Au surface by chemical vapor deposition and it is demonstrated that the contact with a crystalline Au(111) surface gives rise to only out-of-plane strain in both MoS and MoSe layers, whereas no strain generation is observed on polycrystalline Au or SiO /Si surfaces. Scanning tunneling microscopy analysis provides information regarding consequent specific adsorption sites between lower S (Se) atoms in the SMoS (SeMoSe) structure and Au atoms via unique moiré superstructure formation for MoS and MoSe layers on Au(111). This observation indicates that the specific adsorption sites give rise to out-of-plane strain in the TMDC layers. Furthermore, it also leads to effective modulation of the electronic structure of the MoS or MoSe layer.

Conformational analysis of poly(ethylene oxide-alt-ethylene sulfide) (PEOES) has been carried out by ab initio molecular orbital (MO) calculations for a model compound, 2-methoxyethyl methyl sulfide (MEMS), and a refined rotational isomeric state (RIS) scheme developed here. The refined RIS scheme, including the dependence of geometrical parameters as well as interaction energies on conformations of the current and neighboring bonds, is formulated herein. Experimental observations of bond conformations of MEMS and the dipole moment ratio and its temperature coefficient of PEOES in benzene were exactly reproduced by the completely theoretical treatment of the MO−RIS calculations. Thermodynamic and solution properties and weak interactions of PEOES are discussed and compared with those of poly(ethylene oxide) and poly(ethylene sulfide).

The electrochemical properties of a monolayer graphene grown on a Au(111) electrode were studied using cyclic voltammetry (CV) and electrochemical scanning tunneling microscopy (EC-STM). CV and EC-STM measurements in 0.1 M H2SO4 aqueous solution revealed that graphene grown on the reconstructed (22 × √3) Au(111) structure effectively inhibited potential-induced structural transitions between reconstructed (22 × √3) and unreconstructed (1 × 1), and the adsorption/desorption of SO4(2-) ions, which are intrinsic behavior of the bare Au(111) surface. The underlying reconstructed structure was significantly stabilized by covering with monolayer graphene over a wide potential range between -0.2 V and +1.35 V vs Ag/AgCl (saturated KCl), which is much wider than that for bare Au(111) (-0.2 to + 0.35 V vs Ag/AgCl (saturated KCl)). Such high stability has not been reported to date; therefore, these results are considered to be important for understanding the fundamentals of surface reconstruction and also serve to open a new branch of electrochemistry related to graphene/metal-electrolyte interfaces.

Conformational analysis of poly(ethylene imine-alt-ethylene sulfide) (PEIES) has been carried out from ab initio molecular orbital calculations and NMR experiments for its model compound, N-(2methylthioethyl)methylamine (MTEMA). The meso-diad probability, bond conformations, and characteristic ratio of PEIES were predicted by the refined inversional-rotational isomeric state (IRIS) calculations using conformational energies determined from MTEMA. The refined IRIS scheme can treat geometrical parameters and interaction energies as a function of conformations of the present and neighboring bonds. The configurational properties of poly(ethylene imine-alt-ethylene oxide) (PEIEO), poly(N-methylethylene imine-alt-ethylene oxide), and poly(ethylene imine) (PEI) were also evaluated by the refined IRIS computations and compared with those obtained by the conventional method. So long as geometrical parameters are properly chosen, the conventional IRIS method may yield results comparable to those by the refined scheme. Spatial configurations of these polymers depend chiefly on intramolecular attractions between the heteroatoms; the characteristic ratio (〈r 2 〉 0 /nl 2 ) inversely correlates with the strength of N-H‚‚‚X (X ) O, N, or S) attraction: PEIEO with N-H‚‚‚O of -1.75 kcal mol -1 , 〈r 2 〉 0 /nl 2 ) 1.33; PEI with N-H‚‚‚N of -1.54 kcal mol -1 , 3.09; PEIES with N-H‚‚‚S of -0.97 kcal mol -1 , 5.15.

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