Analysis of Birefringence Compensation Using a Quarter-Wave Plate in Solid-State Lasers

Using Jones matrix formulation, the theoretical calculations of birefringence compensation technique for a quarter-wave plate scheme are presented. This scheme was proposed and experimentally demonstrated by W. A. Clarkson et al. (Opt. Lett. 24 (1999) 820). In the present paper we have theoretically confirmed that using this method, even in principle, complete compensation is not possible. However, it is shown quantitatively that this scheme does makes possible effective compensation for the birefringence in as few as several tens of watts of pumping power region, which is an attractive feature for laser-diode (LD) pumped solid-state laser systems. We also found good agreement between our theoretical calculations and experimental results obtained by W. A. Clarkson et al. For example, from the analysis we show that only < 0.1% loss will be generated by about 10 W of heat deposited in the rod. This corresponds to about 30 W of LD pump power, which may generate from 6 to 10 W output power depending upon the conversion efficiency of type lasers     

Multiple superconducting phases in new heavy fermion superconductor PrOs4Sb12

The superconducting gap structure of recently discovered heavy fermion superconductor PrOs4Sb12 was investigated by using thermal transport measurements in magnetic field rotated relative to the crystal axes. We demonstrate that a novel change in the symmetry of the superconducting gap function occurs deep inside the superconducting state, giving a clear indication of the presence of two distinct superconducting phases with twofold and fourfold symmetries. We infer that the gap functions in both phases have a point node singularity, in contrast to the familiar line node singularity observed in almost all unconventional superconductors.     

Formation and properties of n-alkylammonium complexes with layered tri- and tetra-titanates

The formation of n-alkylammonium complexes was studied using Na₂Ti₃O₇ and K₂Ti₄O₉ and the results for both compounds were compared. Alkylammonium complexes could be obtained from H₂Ti₃O₇ and H₂Ti₄O₉·H₂O, which were prepared by HCl treatment of Na₂Ti₃O₇ and K₂Ti₄O₉ respectivel The complexes were formed by exchange of H⁺ with alkylammonium ions. Molecular intercalation of alkylamine was also possible with H₂Ti₄O₉·H₂O. However, alkylammonium complexes were not formed directly from Na₂Ti₃O₇ and from K₂Ti₄O₉. Orientations of alkylammonium ions in the interlayer are also discussed in relation to the structure of the titanate layers.     

The matrix effect on stereoselectivity of olefin cyclopropanation by arylcarbene

Temperature studies of additon of phenylcarbene to styrene showed that stereoselectivity changed rather dramatically as the reaction phase changed.     

Giant Nernst effect in CeCoIn5

We present a study of Nernst and Seebeck coefficients of the heavy-fermion superconductor CeCoIn5. Below 18 K, concomitant with a field-dependent Seebeck coefficient, a large sublinear Nernst signal emerges with a magnitude drastically exceeding what is expected for a multiband Fermi-liquid metal. In the mixed state, in contrast with all other superconductors studied before, this signal overwhelms the one associated with the motion of superconducting vortices. The results point to a hitherto unknown source of transverse thermoelectricity in strongly interacting electrons.     

Two‐dimensional correlation gel permeation chromatography study of aggregate–aggregate interactions during acid‐catalyzed polymerization of triethoxysilyl‐terminated polystyrene

The three‐step polymerization of a well‐defined polymeric silane coupling agent, triethoxysilyl‐terminated polystyrene, catalyzed by acid (H₃PO₄), was traced as a function of the reaction time with gel permeation chromatography (GPC). Time‐resolved GPC traces collected during the polymerization process were then used to construct two‐dimensional (2D) correlation maps via generalized 2D correlation analysis. The results demonstrated that the synchronous and asynchronous 2D correlation GPC spectra directly reflected the dynamic variation of aggregate–aggregate interactions during each step of the polymerization. In particular, it was found that the formation of aggregates among the cyclic trimers (or tetramers) and monomers was critical for the preferential production of pentamers in the reaction system. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3447–3460, 2004     

Rapid analysis of polychlorinated biphenyls in the gas phase with resonance-enhanced two-photon ionization: optimal injection of ions into the ion-trap storage/time-of-flight mass spectrometer.

LI-IT-TOFMS (laser ionization/ion-trap storage/time-of-flight mass spectrometry) is expected to be a powerful tool for environmental monitoring. In the research reported here, real-time LI-IT-TOFMS measurements were carried out on gaseous 2-4 chlorinated PCBs in order to evaluate the applicability of an environmental monitoring method. With respect to ion-trap storage for PCBs, we found that the effect was due to the driving RF voltage on the ring electrode in the ion trap. For PCBs ions produced by laser irradiation, we observed that it was more efficient to reach the center of the ion trap by using a gated RF voltage rather than by using a continuous RF voltage. The ion trajectories in the ion trap were simulated by SIMION 7.0. We found that the voltage of the exit end cap electrode affected both the number of ions trapped and the orbit of ions inside the trap cell. Optimization of this parameter was performed using both simulated and experimental results. The achievable PCBs sensitivity for real-time (1 min) measurement using the LI-IT-TOFMS method was found to be in the pptV range (<0.01 mg/m3N) by means of a comparison with the conventional gas sampling/GS-MS method. A satisfactory proportional relationship was confirmed between the laser-based and conventional results.