Molecular Adsorption Behavior on an Au(111) Surface(STM-other surfaces)

Scanning tunneling microscopy (STM) was used to study molecular adsorption behavior on reconstructed Au(111) surface. The STM images of ethyl 4-[2-(2-pyrazyl)ethenyl]cinnamate (E25PC) molecules adsorbed on Au(111) revealed ordered nucleation of molecular islands at the initial growth stage. The islands grew with spacing 38 Å in rows 77 Å apart. The periodicity of 38 Å×77 Å corresponds to that of STM images of bare Au(111) reconstructed surface in air. The behavior of molecules adsorbed on Au(111) is discussed from a view point of Au(111) herringbone reconstruction

Initial Stage of Molecular Adsorption on Si(100) and H-terminated Si(100) Investigated by UHV-STM(STM-Si(001))

We have investigated the initial stage of adsorption of a conjugated aromatic compound, 1, 4-bis[β-pyridyl-(2)-vinyl]benzene (P2VB), on the clean Si(100)-2×1 surface and the hydrogen terminated Si(100)-2×1-H surface by ultra-high-vacuum (UHV) scanning tunneling microscopy (STM). We found adsorbed molecules cannot migrate on the chemically active Si(100)-2×1 surface, while they can migrate on the chemically inactive hydrogen terminated Si(100)-2×1-H surface until they are trapped to hydrogen-missing dangling bonds. On the clean Si(100)-2×1, we observed four different adsorption directions. An individual molecule appears as two or three bright spots, the brightness and distance between bright spots varying for different cases. Through structural analysis and bias-voltage-dependent STM images, we conclude that the electronic states of Si dimers modulated by the adsorbed molecules are observed instead of the molecules themselves. A simple estimation by considering only the molecular size and shape reproduces the distribution of four different kinds of adsorption structures we observed

Dynamics of Muliticomponent Polymer Systems

報告番号: 乙14868 ; 学位授与年月日: 2000-12-15 ; 学位の種別: 論文博士 ; 学位の種類: 博士(工学) ; 学位記番号: 第14868号 ; 研究科・専攻: 工学系研究科物理工学専

多成分系高分子のダイナミクス

University of Tokyo (東京大学

Crystallization behaviour of biodegradable poly(ethylene succinate) from the amorphous state

Abstract Nonisothermal and isothermal crystallization kinetics of biodegradable poly(ethylene succinate) (PES) from the amorphous state were studied by differential scanning calorimetry (DSC). For the nonisothermal crystallization, there were two crystallization exotherms upon heating from the amorphous state. One major crystallization exotherm located at low temperature corresponded to the real cold crystallization of PES, while the other minor one located at high temperature may correspond to the melt-recrystallization of the unstable crystals formed during the nonisothermal crystallization earlier. Several methods, such as Avrami equation, Tobin equation and Ozawa equation, were applied to describe the nonisothermal crystallization process of PES. Meanwhile, Avrami equation was also employed to study the isothermal crystallization of PES from the amorphous state. Similar to the nonisothermal crystallization the minor crystallization exotherm was also found in the DSC trace upon heating to the melt after the isothermal cold crystallization finished completely, and was attributed to the melt-recrystallization of the unstable crystals formed during the isothermal cold crystallization. Temperature modulated differential scanning calorimetry (TMDSC) was used in this work to investigate the origin of the minor crystallization exotherm located at high temperature, and the TMDSC experiments gave a direct evidence that the origin of the minor crystallization exotherm was from the melt-recrystallization of the originally existed unstable crystals formed through previous crystallization.

Nanoscopic Studies on Polymer Molecules(STM-other surfaces)

A new field of study in the polymer science and engineering is being opened with the use of scanning tunneling microscope (STM), atomic force microscope (AFM), and scanning probe microscope (SPM). In this short review article several examples are given with comments. They are direct observation of poly(macromonomer), structure of a cross-linking domain of a gel, and observation of topochemically photopolymerizable conjugated aromatic compound. Moreover, nanorheological properties of polymer blends are shown as an example of the application of AFM force curve measurements. There are many possibilities of application of SPM to nanoscopic studies on polymer molecules