Taka-Aki Ishibashi

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Thin films of chiral porphyrin J-aggregates have been studied by vibrationally and electronically doubly resonant sum frequency generation (SFG) spectroscopy. It was revealed that the chiral supramolecular structures of porphyrin aggregates in solutions were retained in the thin film samples, and their chirality was determined by using chiral vibrational(More)
We first demonstrated chiral vibrational sum frequency generation (VSFG) in the heterodyne detection, which enables us to uniquely determine chiral second-order nonlinear susceptibility consisting of phase and amplitude and distinguish molecular chirality with high sensitivity. Liquid limonene was measured to evaluate the heterodyne-detected chiral VSFG(More)
Localized singlet diradicals are key intermediates in bond homolyses. The singlet diradicals are energetically much less stable than the σ-bonded species. In general, only one-way reactions from diradicals to σ-bonded species are observed. In this study, a thermal equilibrium between a singlet 1,2-diazacyclopentane-3,5-diyl diradical and the corresponding(More)
A novel SiO(2)-deposited CaF(2) (SiO(2)/CaF(2)) substrate for measuring vibrational sum-frequency generation (SFG) spectra of silane-based chemisorbed monolayers in aqueous media has been developed. The substrate is suitable for silanization and transparent over a broad range of the infrared (IR) probe. The present work demonstrates the practical(More)
Heterodyne-detected vibrationally electronically doubly resonant chiral sum frequency generation (HD-DR chiral SFG) spectroscopy has been developed for the study of chiral molecules with chromophores. The method enables us to detect and distinguish chiral molecules with high sensitivity and to obtain information on molecular vibrations. Strong enhancement(More)
CN stretch bands of singlet and triplet cyclopentane-1,3-diyl diradicals (1,3-di(4-cyanophenyl)-2,2-dimethoxyoctahydropentalene-1,3-diyl and 1,3-di(4-cyanophenyl)-2,2-dimethyloctahydropentalene-1,3-diyl) were observed by time-resolved IR spectroscopy. CN stretching wavenumbers of the singlet and triplet diradicals were downshifted by 10 and 19 cm(-1) from(More)
The behavior of water molecules at the surface of nonionic surfactant (monomyristolein) and effects of monovalent ions on the behavior are investigated using the heterodyne-detected vibrational sum frequency generation spectroscopy. It is found that water molecules at the surface are oriented with their hydrogen atoms pointing to the bulk, and that the(More)
We have synthesized double-chain disulfides of adenine with different chain lengths (n = 2, 4, 5, 9, and 10) and studied their self-assembled monolayers (SAM) on gold surface by IR-UV doubly resonant sum frequency generation spectroscopy with the help of DFT calculation. A versatile way to investigate the orientation angle of functional groups of SAMs and(More)
Heterodyne-detected (phase-sensitive) vibrational sum frequency generation spectroscopy was used to investigate molecular structures of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayers on water (Langmuir monolayer) and monolayers on a fused silica substrate (Langmuir-Blodgett [LB] monolayer). The spectral features in the CH stretching region(More)
Low-frequency surface vibrations were observed on a rutile TiO(2)(110) surface covered with trimethyl acetate (TMA) by using fourth-order Raman spectroscopy. The TMA-covered surface interfaced to air was irradiated with 18-fs light at a wavelength of 630 nm. A pump pulse excited vibrational coherence of Raman-active modes and a probe pulse interacts with(More)