Einstein<Emphasis Type="Italic">A</Emphasis>-coefficients for rotational transitions in the ring-chain isomer of C<Subscript>5</Subscript>H<Subscript>2</Subscript>

Laboratory formation of four isomers of C⁵H² molecule is reported and detection of the ring-chain isomer (isomer 1) of C₅H₂ in cosmic objects has been suggested. For identification of a molecule in cosmic objects, one of the required input data is EinsteinA-coefficients (radiative transition probabilities) for the molecule. Here, we report EinsteinA-coefficients for electric dipole transitions in the ring-chain isomer of C₅H₂ among the rotational levels of the ground electronic and ground vibrational states up to 21 cm⁻¹.     

Diode-pumped intra-cavity doubled Nd:LuVO4 laser at 458 nm

We have demonstrated a diode-pumped intra-cavity frequency doubling Nd:LuVO₄ laser operating at 916 nm with a Z-folded cavity. A 10-mm long LBO crystal, cut for critical type I phase matching at 912 nm, is used for the experiment. A maximum output power of 330 mW at 458 nm has been achieved at pump power of 22 W. The optical-to-optical conversion efficiency and slope efficiency is 1.5% and 2.3%, respectively. The power instability at the maximum output power in 30 min is better than 3%.     

Measurement of the elastic constants of a columnar SiC thin film

The technique of resonant ultrasound spectroscopy was used to measure the elastic properties of a polycrystalline cubic silicon carbide (3C-SiC) thin film. The film, grown on a silicon (100) substrate, was 1.69 microns thick with columnar crystalline grains and a (111) texture. The substrate with the film was placed between two transducers and the resonant frequencies were measured; measurements were repeated after selective, timed dry etching of the film, allowing a determination of the elastic constants of the film alone. The film elastic constants, c(11)=371 and c(12)=146 GPa, were within a few percent of the literature values (c(11)=386, c(12)=136 GPa) of crystalline 3C-SiC. However, the film elastic constant c(44), 111 GPa, was significantly smaller than the bulk literature value, 254 GPa. For the film, c44 approximately (c(11)-c(12))/2, indicating that, quite unlike a bulk 3C-SiC crystal, the thin film is elastically isotropic.     

Surface plasmon sensor with gold film deposited on a two-dimensional colloidal crystal

A sensor based on surface plasmon resonance (SPR) of plasmonic crystals fabricated via a colloidal-crystal-assisted templating method is studied. Plasmonic crystals are prepared by depositing a thin gold (Au) layer onto a two-dimensional array of polystyrene spheres self-assembled on a quartz substrate. The enhanced transmission as a result of the SPR of Au plasmonic crystals, which are immersed in different ambient liquids, are measured and compared with that of polystyrene (PS) microsphere templates of different sizes, both before and after removal of Au nanoprisms formed on the quartz substrate through pores among the spheres. It is found that the measured sensitivities exhibit a linear dependence on the refractive index of the surrounding medium and are linked to coupling effects between SPRs on the corrugated Au film and nanoislands. The feasibility of the SPR system in molecular monolayer detection is further demonstrated through a formation of alkanethiolate self-assembled monolayers on the Au film surface, which causes a 4 nm red-shift of the main SPR. PACS  07.07.Df; 73.20.Mf; 78.66.-w; 81.16.Dn     

An improved transmission line laser model for multimode laser diodes incorporating thermal effects

An improved transmission line model to study the thermal effects in semiconductor laser diodes is reported in this paper. The temperature effects in the laser characteristics are obtained by incorporating temperature dependent gain and carrier density equations for the laser cavity. These primary factors are introduced in the regular transmission line laser model to estimate the static and dynamic characteristics of an 1.3μm InGaAsP double heterostructure laser diode. The results show good agreement with the experimental observation and solution of rate equations referred in the literature. The key feature of this model is that it provides the laser spectra at various temperatures. Based on the model, time dependent evolution of optical spectrum, temperature dependent optical output and frequency chirp are evaluated. Further the distribution of photon and electron density within the cavity is also determined.     

Erratum to Formation and control of Au and Ag nanoparticles inside borate glasses using femtosecond laser and heat treatment

We report the spectroscopic properties of femtosecond laser-irradiated sodium-alumino-borate glass doped with silver and gold ions. We precipitated gold and silver nanoparticles by laser irradiation and annealing at 400°C for 30 min. The irradiation and annealing treatment produced different absorption and emission characteristics in Au³⁺ doped and Au³⁺, Ag⁺ codoped glasses, and the possible mechanisms of the observed results are discussed. The size of the nanoparticles was estimated by TEM and absorption band analysis.     

Lee–Yang Problems and the Geometry of Multivariate Polynomials

We describe all linear operators on spaces of multivariate polynomials preserving the property of being non-vanishing in open circular domains. This completes the multivariate generalization of the classification program initiated by Pólya–Schur for univariate real polynomials and provides a natural framework for dealing in a uniform way with Lee–Yang type problems in statistical mechanics, combinatorics, and geometric function theory.