Ferroelectric Smectic C Liquid Crystal Phase with Spontaneous Polarization in the Direction of the Director.

In the previous study, the existence of an unidentified ferroelectric smectic phase is demonstrated in the low-temperature region of the ferroelectric smectic A phase, where the layer spacing decreases with decreasing temperature. In the present study, the phase is identified by taking 2D X-ray diffraction images of a magnetically oriented sample while allowing it to rotate and constructed a 3D reciprocal space with the sample rotation angle as the third axis for the whole picture of the reciprocal lattice vectors originating from the smectic structure. Consequently, circular diffraction images are obtained when the reciprocal lattice vectors are evenly distributed on the conical surface at a certain inclination angle in the reciprocal space.

Photoionization of environmentally polluting aromatic chlorides and nitrides on the water surface by laser and synchrotron radiations.

The detection limits and photoionization thresholds of polycyclic aromatic hydrocarbons and their chlorides and nitrides on the water surface are examined using laser two-photon ionization and single-photon ionization, respectively. The laser two-photon ionization methods are highly surface-selective, with a high sensitivity for aromatic hydrocarbons tending to accumulate on the water surface in the natural environment due to their highly hydrophobic nature. The dependence of the detection limits of target aromatic molecules on their physicochemical properties (photoionization thresholds relating to excess energy, molar absorptivity, and the octanol-water partition coefficient) is discussed.

Development of an anion probe: detection of sulfate ion by two-photon fluorescence of gold nanoparticles.

Anion-selective detection is demonstrated for sulfate ion in aqueous solutions by using two-photon excited fluorescence of gold nanoparticles (AuNPs) modified with a thiourea-based anion receptor, bis[2-(3-(4-nitrophenyl)thioureido)ethyl]disulfide. The fluorescent intensity increased with the change of the sulfate concentration in the solution from 10(-4) to 10(-3) M. In comparison with an unadsorbed receptor molecule in bulk acetonitrile solution, the molecule on AuNPs in water showed improved affinity for sulfate ion.