The University of Tokyo · Materials Science
Professor Satoshi Watanabe's research lab specializes in advanced materials and surface science, focusing on the electronic and structural properties of low-dimensional systems, including atomic-scale wires and functional surfaces. The lab investigates phenomena such as two-color laser control in ionization dynamics, conductive polymer electrodes for flexible actuators, and the atomic-scale electronic structures of semiconductor surfaces. Their work bridges theoretical first-principles calculations with experimental characterization, particularly in scanning tunneling microscopy and electroactive materials. The lab also explores smart materials with tunable responses to electric fields, such as bending polyurethane films with tailored chemical structures.
Figures are computed from collected data and may differ slightly.
Two-color phase control in the total ion yield of ionization is successfully demonstrated in a tunneling regime by using a 100-fs Ti:sapphire laser and its third harmonic. Adding the third harmonic with an intensity of only 10% enhances the ion yield by a factor of 7. In photoelectron spectra, above threshold ionization peaks due to the third harmonic disappear when two colors are superimposed, resulting in a continuum spectrum. This shows two-color interference clearly. The intensities of high-
As an electrode for a bending-electrostrictive polyurethane actuator, we prepared a wrinkled polypyrrole electrode, expecting the following two effects because the wrinkled electrode could easily elongate by smoothing the wrinkles: (1) conductivity of the electrode would not decrease with the field-induced surface elongation of the actuator, and (2) the electrode would not constrain the actuation. The wrinkled electrode was prepared through in situ deposition of polypyrrole onto the polyurethane
The scanning-tunneling-microscopy (STM) images of the Si(111)\ensuremath{\surd}3 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}3- Ag surface have been calculated from first principles for a structural model of the surface recently proposed, or the modified honeycomb-chained-trimer model, which is consistent with reported photoemission and inverse-photoemission spectra. The results show excellent agreement with reported STM images. Each bright spot corresponding to a protrusion in the repo
Electronic structures of several atomic wires on an H-terminated Si(100)2\ifmmode\times\else\texttimes\fi{}1 surface have been examined by using first-principles calculations within the local-density-functional approach. Several dangling-bond (DB) wires, which are constructed by extracting H atoms from the surface, have been examined and found to have different characteristics depending on their structures. Electronic states near the Fermi energy are localized around the wire on the atomic scale
Application of an electric field bent a polyurethane single-layer film. The bending direction depended on the chemical structure of the polyurethane. A film made from a polyurethane (N-PU) that had phenylimino groups in its structure bent toward the anode side. On the other hand, another film made from a different kind of polyurethane (Nt-PU) that had nitrophenyl groups bent toward the cathode side. Measurements of the space-charge distributions in the films using a pulsed electroacoustic method
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