Chiral recognition by enantioselective liquid chromatography: Mechanisms and modern chiral stationary phases

Experiments on ultrathin anisotropic arrays of subwavelength optical antennas display out-of-plane refraction. A powerful three-dimensional (3D) extension of the recently demonstrated generalized laws of refraction and reflection shows that the interface imparts a tangential wavevector to the incident light leading to anomalous beams, which in general are noncoplanar with the incident beam. The refracted beam direction can be controlled by varying the angle between the plane of incidence and the antenna array.

http://www.zenogaburro.it/papers/2012_Nano_Aieta_OutOfPlane.pdf

Out-of-Plane Reflection and Refraction of Light by Anisotropic Optical Antenna Metasurfaces with Phase Discontinuities

We investigate the transmission of evanescent waves through a slab of photonic crystal and explore the recently suggested possibility of focusing light with subwavelength resolution. The amplification of near-field waves is shown to rely on resonant coupling mechanisms to surface photon bound states, and the negative refractive index is only one way of realizing this effect. It is found that the periodicity of the photonic crystal imposes an upper cutoff to the transverse wave vector of evanescent waves that can be amplified, and thus a photonic-crystal superlens is free of divergences even in the lossless case. A detailed numerical study of the optical image of such a superlens in two dimensions reveals a subtle and very important interplay between propagating waves and evanescent waves on the final image formation. Particular features that arise due to the presence of near-field light are discussed.

/pdf/subwavelength-imaging-in-photonic-crystals-1cessc1emt.pdf

Subwavelength imaging in photonic crystals

Multipolar interactions in f -electron systems: The paradigm of actinide dioxides

We discuss linear and nonlinear optical wave propagation in a left-handed medium (LHM) or medium of negative refraction (NRM). We use the approach of characterizing the medium response totally by a generalized electric polarization (with a dielectric permittivity {tilde {var_epsilon}}(w, {rvec k})) that can be decomposed into a curl and a non-curl part. The description has a one-to-one correspondence with the usual approach characterizing the LHM response with a dielectric permittivity {var_epsilon}<0 and a magnetic permeability {mu}<0. The latter approach is less physically transparent in the optical frequency region because the usual definition of magnetization loses its physical meaning. Linear wave propagation in LHM or NRM is characterized by negative refraction and negative group velocity that could be clearly manifested by ultra-short pulse propagation in such a medium. Nonlinear optical effects in LHM can be predicted from the same calculations adopted for ordinary media using our general approach.

/pdf/linear-and-nonlinear-wave-propagation-in-negative-refraction-1sfiqyy3cj.pdf

Linear and nonlinear wave propagation in negative refraction metamaterials

Magnetic properties were investigated on a single-crystalline DyB 2 C 2 compound with the tetragonal structure. Spontaneous magnetizations appear along the a- and [1 1 0]-directions below T C =15.3 K. A very small shoulder is observed only along the c -axis at T Q =24.7 K, although large λ-type anomalous specific heats are observed at T C and T Q . There exists a large magnetic anisotropy in the tetragonal basal plane which is observed in magnetization processes below T C . Neutron powder diffraction experiments reveal that magnetic reflections are observed only below T C . In the magnetically ordered phase, the Dy moments are arranged to be perpendicular to neighbors along the c -axis. The results are well interpreted by postulating that the phase between T C and T Q is an antiferroquadrupolar ordered one. DyB 2 C 2 is a novel compound with a high antiferroquadrupolar ordering temperature of 24.7 K.

Antiferroquadrupolar ordering and magnetic properties of the tetragonal DyB2C2 compound

Magnetic susceptibility, magnetization process, specific heat, ultrasonic velocity, and inelastic neutron scattering experiments were performed on powdered and single-crystalline ${\mathrm{TmAu}}_{2}$ samples. ${\mathrm{TmAu}}_{2}$ with a simple body-centered tetragonal ${\mathrm{MoSi}}_{2}$-type structure undergoes a transition to an antiferromagnetic state at ${T}_{N}$ of 3.2 K. An anomaly at 7.0 K is observed in the temperature dependence of specific heat and magnetic susceptibility. A very large softening beyond 50% from 300 down to 7.0 K is also observed in the temperature dependence of the elastic constant of the ${C}_{11}\ensuremath{-}{C}_{12}$ mode. The results reveal clearly that the anomaly at 7.0 K ${(=T}_{Q})$ originates from a ferroquadrupolar ordering with an orthorhombic $\ensuremath{\gamma}$-symmetry-lowering mode. Separation between the ground and the first excited singlet states of $4f$ levels is so small in the quadrupolar ordered phase and a transition probability between these states is so extremely large that there occurs a Van Vleck antiferromagnetic transition at 3.2 K by exchange-induced magnetic moments arising from the transition between the ground and the first excited singlet states.

Quadrupolar ordering and magnetic properties of tetragonal TmAu 2

Synthesis of enantiopure phthalides including 3-butylphthalide, a fragrance component of celery oil, and determination of their absolute configurations.

Masashi Kosaka

Papers

Antiferroquadrupolar ordering and magnetic properties of the tetragonal DyB2C2 compound

Quadrupolar ordering and magnetic properties of tetragonal TmAu 2

Synthesis of enantiopure phthalides including 3-butylphthalide, a fragrance component of celery oil, and determination of their absolute configurations.

Convergent synthesis of the HIJKLM ring fragment of ciguatoxin CTX3C

Magnetic properties of single-crystalline RNiC2 compounds (R = Ce, Pr, Nd and Sm)