Laser desorption supersonic jet spectroscopy, which can enable the conformer-selected measurements, was improved by optimizing the matrix substances and introducing a high-pressure supersonic jet expansion to obtain high desorption efficiency and high jet-cooling effect. The improved laser desorption supersonic jet technique was applied to catecholamine neurotransmitters and their relevant molecules. By using resonance enhanced multiphoton ionization and UV-UV hole burning spectroscopies, the number of conformers of each molecule was determined. By comparing them, we found a propensity rule, named as “doubling rule”, in the conformational evolution of relevant molecules. However, the numbers of conformers of catecholamines are much less than the expected ones by the doubling rule. Thus we concluded that the numbers of conformers of catecholamines are specifically small. We discussed the reason of decreasing the number of conformers of catecholamines, and which was interpreted as due to the specific flexibility of catecholamines.
Liquid interfaces are ubiquitous and of fundamental importance in many physicochemical phenomena, such as atmospheric reactions on aerosol particles, cavitation bubbles, biochemical reactions, and so forth. The interfacial region is very limited in space and has unique properties compared to the bulk due to its heterogeneous environment. Molecular simulation is a powerful technique to elucidate and predict physical and chemical properties of interfaces with thickness of nm order. In this review, we focus on the recent progress of the simulation studies of molecular structure, vibrational spectroscopy, and transport phenomena at the interfacial region. A key experimental technique to elucidate interfacial molecular structure is the interface-selective vibrational sum frequency generation (VSFG) spectroscopy. A close collaboration of VSFG studies with molecular simulation has opened an avenue for understanding new aspects of the structures of aqueous surfaces. We discuss some important properties of water to interpret the interfacial vibrational spectra. We further review the recent development of the simulation studies for the transport phenomena associated with condensation and evaporation at liquid interfaces.
Soft x-ray spectroscopies which utilize electronic transition of core electrons are known as a powerful tool for observing electronic structures, and are extensively applied to solid and gaseous samples in vacuum. While soft x-ray requires a vacuum because of its low penetration ability, one cannot hold liquid phase samples in vacuum due to the vaporization of liquids. Therefore, soft x-ray measurement of liquid samples was one of the difficult experiments only a decade ago. Recently, extensive developments in experimental techniques have enabled the application of x-ray emission and absorption spectroscopy to liquid and solution samples. In this article, our recent investigations on electronic state concerning liquid structure of water using soft x-ray beamline BL17SU in third generation synchrotron facility SPring-8 are reviewed. In addition, the development of experimental apparatus dedicated to the research of liquid and solution samples is presented.
Functionalities of organic semiconductors are governed not only by individual molecular properties but also by their weak intermolecular interactions in various conformations. The individual molecular property has been widely investigated in detail; on the other hand, the weak intermolecular interaction is difficult to investigate precisely due to the presence of the extrinsic energy broadening in organic solids such as structural disorders. Here we review the recent progress in the valence band dispersion of organic materials studied by using angle-resolved photoemission spectroscopy (ARPES). The novel ARPES technique reveals the precise band-dispersion measurement of sub-0.1-eV scale in molecular crystalline films, which enables us to discuss the quite weak but essential intermolecular interaction systematically based on the chemical substitution of constituent elements in the molecule. The precise and systematic band-dispersion measurement would be a credible approach towards the comprehensive understanding of the intermolecular interaction and the resultant charge transport property as well as their tuning by substituents in organic molecular systems.
In recent years much of interest in atmospheric chemistry has been focused on atmospheric aerosols. In this article, laboratory kinetic studies and related quantum chemical theoretical studies on typical processes of formation and transformation of organic aerosols have been reviewed. Specifically, it targets on the topics of heterogeneous reactions of atmospheric O3 and OH with organic compounds at the surface of aerosols, and aqueous-phase reactions of dialdehydes (glyoxal and methylglyoxal) in cloud and aerosol particles. In order to attain better understanding on such processes, fundamental studies based on molecular science are needed, and closer collaboration between atmospheric chemistry and theoretical computational chemistry is proposed.
Single-walled carbon nanotubes are one of the candidate materials for the next generation electronics, such as printed, flexible, stretchable and wearable electronics due to their chemical stability, printability, flexibility, light-weight, and unique mechanical properties. In particularly, a combination of single-walled carbon nanotubes with electrolytes reveals rich and novel functionalities. This review describes recently demonstrated functional devices, such as inkjet-printed, extremely flexible, electrolyte-gated transistors.
Organic functional crystals with novel π-electronic states such as (super)conductivity, (anti-/ferro)magnetism, etc. have been vigorously developed. On the other hand, researches of hydrogen-related functionalities such as (anti-/ferro)electrics, proton (super)conductivity, etc. have been also extensively performed. In this article, the novel π-electron-hydrogen concerted organic materials and their functionalities are introduced. This phenomenon with dynamically coupled π electron-hydrogen might be related to biochemical cascade reactions and applicable to novel organic surface and devices.