Hiroo Matsuda

Photofabrication of surface relief structure: mechanism and application

Abstract In order to elucidate the photoinduced surface relief (PSR) phenomenon on azobenzene polymer film, the formulation of the PSR formation process is established analytically from Navier–Stokes equation on the basis of our viscous fluid model. The experimental data obtained by the systematic studies for two-beam coupling and one-dimensional (1D) Gaussian beam irradiation are reproduced very well by the model calculation. The good coincidence assures the feasibility of our theoretical model. Furthermore, an example for applying this phenomenon to 2D micro-image recording and/or high-density optical data storage is presented.

External field-induced orientation of DAST nanocrystals in the dispersion state and the fixation

We have prepared an dispersion of 4-dimethylamino-N-methylstilbazolium p-toluenesulfonate (DAST) nanocrystals using the reprecipitation method and have spectroscopically measured their orientation in an electric or magnetic field. As a result, we could observe reversible and efficient contrast change that depends on the on-off of applied field. In addition, with controlling the orientation of DAST nanocrystals by the external field, the immobilization was performed using light-cured polymer and the light irradiation. These materials may be applied to the display device or polarized light filter.

Phase analysis of vibrational wavepackets in the ground and the excited states in polydiacetylene

Wavepackets of C-C and C=C stretching modes in the ground state start to oscillate π-out-of-phase with C≡C stretching mode. All the three modes in the self-trapped states observed indicate an acetylene-like structure not a butatriene-like.

Two-dimensional spectroscopy by spectrally resolved real-time resonant coherent Raman scattering in polydiacetylene

Spectrally resolved real-time coherent resonant Raman scattering was observed by a 4-fs ultrashort pulse with a spectrally resolving multi-channel lock-in amplifier and was identified by a theoretical calculation. An introduced optical frequency- and vibrational time-resolved two-dimensional spectrum reveals the electronic ground-state dynamics below the absorption edge.

Real time tracking of the peaks in transition difference spectra during vibrational periods in PDA

Molecular dynamics are investigated using spectrally resoled pump-probe measurement. Stokes shift associated with geometrical relaxation and electronic spectral change caused by lattice vibration are directly observed in time by a novel peak-energy tracing method.