Stepwise two-photon absorption (2PA) processes are becoming an important technique because it can achieve high reductive photochemical reactions with visible and near infrared light and intensity-gated high spatiotemporal selectivity with much lower power thresholds than those of the simultaneous 2PA. However, excited states generated by stepwise 2PA (higher excited states and excited states of transient species) are so short-lived that the efficiency for the stepwise 2PA induced photochemical reactions is usually quite low. Here, we demonstrated that the electron of the higher excited state of perylene bisimide (PBI) can be efficiently extracted by CdS nanocrystals (NCs) in a nanohybrid of PBI-coordinated CdS NCs.
Highly conducting molecular wires are vital to realize molecular scale electronics. In this account, I discuss our recent efforts to improve the conductance of single-molecule junctions. When electron-rich Ru tetraphosphine fragments were embedded in π-conjugated organic molecular wires, single-molecule conductance obtained by the scanning tunneling microscope junction method drastically improved. Long-range conduction properties, conduction carrier control, and molecular switching function were achieved by multinuclear systems.
A reflectron time-of-flight mass spectrometer (RTOF-MS) is a powerful tool for achieving a high resolution in mass analysis of various ions. In this article, we present a novel design of RTOF-MS equipped with an additional electrostatic lens in front of a conventional grid-less ion reflector. This design improves its performance particularly in the convergence of the ion beam of analytes initially spread over a large volume in the acceleration region, which was intended to solve the problem of low-detection efficiency of conventional RTOF-MS for such dispersed samples. The novel reflectron is designed with the aid of ion-trajectory simulation. Being implemented to our experimental setup for gas-phase metal clusters, it shows improved performance as demonstrated by evaluating the spatial profile of the ion beam as well as the mass resolution.
To improve water-splitting photocatalyst activity, it is effective to load metal/metal oxide nanoparticles as cocatalysts. However, it is difficult to precisely control their particle size and electronic state using conventional methods. In this study, we attempted to create a highly active water-splitting photocatalyst by loading synthesized platinum (Pt) nanoclusters about 1 nm in size onto a visible light–driven water-splitting graphitic carbon nitride (g-C3N4) photocatalyst. As a result, the Pt nanocluster–loaded g-C3N4 photocatalyst showed 3.5-time higher hydrogen evolution activity compared with that prepared using the conventional photodeposition method. It is presumed that the improvement was due to the finer particle size and the metallic electronic state of the Pt cocatalyst prepared using our method. This novel cocatalyst preparation method is expected to enable the development of various photocatalysts with high activity and to contribute to the construction of a next-generation energy society.
Coordination polymers are inorganic-organic hybrid materials composed of metal ions and bridged organic ligands. We are synthesizing novel coordination polymers for application to various electronic devices. Organic thin-film solar cells are particularly interesting photoelectric conversion devices, therefore we are focusing on developing new thin-film solar cells based on coordination polymers. In this paper we report on our recent work on the application of coordination polymers to electronic devices.