Polarization characteristics of an electromagnetic wave scattered from a slightly random surface: +45° polarized incidence

Abstract

The present paper deals with the scattering of an obliquely polarized electromagnetic (EM) wave from a slightly rough surface, which is assumed to be a two-dimensional (2D), homogeneous and isotropic Gaussian random field. In contrast to the cases of TE(s) and TM(p) polarized incidence, the scattering profile for an obliquely polarized incidence is not symmetric with respect to the incident plane, despite the fact that the random surface is statistically isotropic.     

Radiation-Induced Polymerization of Acrylic Esters at High Pressure and Pressure-Volume Behavior of Polymer-Monomer Coexistence System as Polymerized

Pressure-volume (P-V) behavior and radiation-induced polymerization of methyl and n-butyl acrylic esters (MA and BA, respectively) were studied up to 7000 kg/cm² at 20°C. The P-V isotherms broke at 1900 and 1200 kg/cm² for MA and BA, respectively. The P-V isotherm for MA was not smooth in the pressure range between 3500 and 4000 kg/cm². The polymerization behavior varied with change in the P-V behavior; the polymerization rates were maximum at 1800 kg/cm for MA and 1000 kg/cm² for BA, and then minimum at 1900 kg/cm² for MA and 1100 kg/cm² for BA. The polymerization rates increased again above the pressures giving the minimum rates up to about 3000 kg/cm². Above 3000 kg/cm² the pressure dependence of the rates decreased up to 4000 and 4500 kg/cm² for MA and BA, respectively. Above these pressures, the pressure dependence of polymerization rates increased again. The P-V isotherms of as-polymerized polymer-monomer coexistence systems showed characteristic behavior near the polymerization pressure. From a comparison of these polymerizations and P-V behavior with those of methacrylic esters, we propose that acrylic esters align at high pressure and that freedom of rotation of ester group plays an important role in the mode of pressure-induced alignment of monomer molecules.     

Component Crystallization and Physical Collapse during Freeze-Drying of L-Arginine-Citric Acid Mixtures

Component crystallization and physical collapse during freeze-drying of aqueous solutions containing protein-stabilizing L-arginine and citric acid mixtures were studied. Freeze-drying microscopy (FDM) and thermal analysis of the solute-mixture frozen solutions showed collapse onset at temperatures (T(c)) approximately 10°C higher than their T(g)'s (glass transition temperatures of the maximally freeze-concentrated solute phase). Experimental freeze-drying of these solutions at a low chamber pressure showed the occurrence of physical collapse at shelf temperatures close to or slightly higher than the T(c). Slower ice sublimation at higher chamber pressures induced the physical collapse from lower shelf temperatures. The large effect of chamber pressures on the collapse-inducing shelf temperatures confirmed significance of the sublimation-related heat loss on the sublimation interface temperature during the primary drying. Drying of the single-solute L-arginine solution resulted in cake-structure solids composed of its anhydrous crystal. Thermal and powder X-ray diffraction (PXRD) analysis suggested slow crystal nucleation of L-arginine dihydrate in the frozen solutions. Characterization of the frozen solutions and freeze-dried solids should enable rational formulation design and process control of amino acid-containing lyophilized pharmaceuticals.     

Infrared multiple photon decomposition of CHBrF2 induced by a free-electron laser

2 . The laser generates an intense infrared macropulse with a duration of 17 μs; the macropulse consists of a train of 380 micropulses, each of which has a duration of a few picoseconds. The fluence of a macropulse was estimated to be about 16 Jcm^-2 at a beam waist. Peak wavelengths were set in the range of 9–10 μm. The macropulse induced the IRMPD of 1 and 5 Torr CHBrF₂; most of molecules in the focal region seemed to decompose at a wavelength of 9.3 μm. The mechanism is the initial decomposition of CHBrF₂ to CF₂ and HBr, followed by the dimerization of CF₂ to form C₂F₄. The decomposition was found to be isotopically selective at 9.7 μm; the final product C₂F₄ had a ¹³C atomic fraction of 6%. Th e addition of CO₂ to CHBrF₂ significantly decreased the yield of C₂F₄. vibrationally excited CHBrF₂ molecules produced by laser pulses were efficiently deactivated by CO₂ molecules. Received: 7 October 1996     

Synthetic Control of Spectroscopic and Photophysical Properties of Triarylborane Derivatives Having Peripheral Electron‐Donating Groups

The spectroscopic and photophysical properties of triarylborane derivatives were controlled by the nature of the triarylborane core (trixylyl‐ or trianthrylborane) and peripheral electron‐donating groups (N,N‐diphenylamino or 9H‐carbazolyl groups). The triarylborane derivatives with and without the electron‐donating groups showed intramolecular charge‐transfer absorption/fluorescence transitions between the π orbital of the aryl group (π(aryl)) and the vacant p orbital on the boron atom (p(B), π(aryl)–p(B) CT), and the fluorescence color was tunable from blue to red by the combination of peripheral electron‐donating groups and a triarylborane core. Detailed electrochemical, spectroscopic, and photophysical studies of the derivatives, including solvent dependences of the spectroscopic and photophysical properties, demonstrated that the HOMO and LUMO of each derivative were determined primarily by the nature of the peripheral electron‐donating group and the triarylborane core, respectively. The effects of solvent polarity on the fluorescence quantum yield and lifetime of the derivatives were also tunable by the choice of the triarylborane core.     

High Spatial Resolution Electro -Optic Field -Mapping for Three Orthogonal Field Components in a Micro -Structured Electrode

The optically based technique of electro-optic (EO)sampling has been used for diagnosing the internal high-speed signals of integrated circuits [1]. One of the features that make the EO sampling technique very promising is a minimal probe: the EO sampling technique does not require an electrode and ground plane incorporated as part of a probe so that, compared with conventional metal probes, the invasiveness of an EO probe is minimal.     

Tunable error-free optical frequency conversion of a 4 ps opticalshort pulse over 25 nm by four-wave mixing in a polarisation-maintainingoptical fibre

Error-free, tunable optical frequency conversion of a transform-limited 4.0 ps optical pulse signal is demonstrated at 6.3 Gbit/s using four-wave mixing in a polarisation-maintaining optical fibre. The process generates 4.0-4.6 ps pulses over a 25 nm range with time-bandwidth products of 0.31-0.43 and conversion power penalties of less than 1.5 dB     

Size separation and size determination of liposomes

We developed a method for separating liposomes by size and determining their average diameters. Liposomes with different average diameters were separated on a monolithic silica capillary column, and the size of the liposomes corresponding to each peak was determined online with a dynamic light scattering detector coupled to the capillary liquid chromatography system. The calculated diameters for the separated liposomes were similar to the diameter values measured in batch mode. We demonstrate that this combination of a monolithic capillary column and light scattering detection could be used for size separation of liposomes and could provide more details about average diameters than batch-mode analysis.     

Scattering of an electromagnetic wave from a slightly random dielectric surface: Yoneda peak and Brewster angle in incoherent scattering

Abstract

The scattering of an electromagnetic wave from a two-dimensional, slightly rough dielectric surface is studied based on the stochastic functional approach. It is shown that in the case of TM(p)-polarized incidence there exists a zero in the incoherent scattering at the angle we call the ‘Brewster scattering angle’, which depends on the incident angle in contrast to the Brewster angle of coherent reflection which is independent of the incident angle, that a ‘quasi-anomalous scattering’ can generally occur in the optically denser medium at the critical angle of total reflection in both TE(s)- and TM(p)-polarized incidence, regardless of which side of the random surface is illuminated, and that the Yoneda peak in the x-ray scattering can be interpreted as a special case of the quasi-anomalous scattering which becomes sharper when the relative refractive index becomes closer to unity as in the x-ray region. Cross-polarized scattering and enhanced backscattering due to the second-order effect are also calculated.