Nd:YLF laser at cryogenic temperature with orthogonally polarized simultaneous emission at 1047 nm and 1053 nm.

A Nd:YLF laser at cryogenic temperature is demonstrated for the first time with orthogonally polarized simultaneous emission at 1047 nm and 1053 nm. By exploring the temperature dependence of the fluorescence and the absorption spectra from the Nd:YLF crystal, the feasibility of simultaneous emission at low temperature is achieved. Due to the local heating from the pump absorption, the optimal temperature with respect to the pump power for balancing output powers of simultaneous emission is thoroughly explored. At the optimal temperature of 138 K, the total output power of the simultaneous emission can reach 3.1 W at an incident pump power of 7.9 W, corresponding to the optical to optical slope efficiency up to 43%.

Identification and validation of quantitative trait loci conferring tan spot resistance in the bread wheat variety Ernie.

Tan spot, caused by Pyrenophora tritici-repentis, is a foliar disease of wheat, and it can inflict serious reduction in grain yield and quality. The bread wheat variety Ernie was found to be immune to this disease in Australia, and its genetic control was investigated by quantitative trait loci (QTL) analysis using a doubled haploid population. Eight QTL were identified in this population from three independent trials, and four of them were derived from the parent Ernie. The most significant QTL was located on chromosome arm 2BS, explaining 38.2, 29.8 and 36.2% of the phenotypic variance, respectively, in these trials. The effects of the 2BS QTL were further validated in four additional populations. The presence of this single QTL reduced disease severity by between 29.2 and 67.1% with an average of 50.5%. The significant effects of this QTL and its consistent detection across all the trials with different genetic backgrounds make it an ideal target for breeding programmes as well as for its further characterization. Data from this study also showed that neither plant height nor heading date significantly affects tan spot resistance.

The C3-bending levels of the C3-Ar complex studied by optical spectroscopy and ab initio calculation.

The A-X electronic transition of C3-Ar, near 405 nm, has been studied by both laser-induced fluorescence and wavelength-resolved emission techniques. Emission spectra have been recorded from 14 vibrational levels of the A state of C3-Ar; these spectra consist of progressions in the ground state v2 and v4 vibrations (the in- and out-of-plane C3-bending motions, respectively). With increasing bending excitation, these ground state levels shift progressively downwards compared to those of free C3, indicating that the van der Waals complexes are becoming more tightly bound. The level structure of the two vibrations of C3-Ar has been fitted to a perturbed harmonic oscillator model, where the potential function has the form V = V1r cos theta + V2r2 cos 2theta (r is the amplitude of the C3-bending motion and theta gives the orientation of the rare gas atom relative to the plane of the bent C3 molecule). Ab initio calculations have been carried out for C3-Ar at the coupled-cluster singles, doubles (and triples)/correlation consistent polarization valence quadruple-zeta level. They predict that the C3-Ar complex is nearly T shaped at equilibrium, and that as the C3 molecule bends away from the linear configuration, the preferred orientation is "arrow" shaped. From the results of the best fit to the model and the emission spectral intensities, the relative orientation of the out-of-plane pi electron of the A-state complex and the Ar atom has been estimated. No bands of the Ar complex were found near the C3, A-X, (0,0) band, consistent with the fact that the A 1Piu, upsilon = 0 level of free C3 is strongly perturbed by triplet levels. In the excitation spectra of the Ar complex, the bands with upsilonb' > 0 show redshifts of about 16-36 cm(-1) compared to those of free C3, indicating that the A-state complex in these levels is more tightly bonded than the X-state complex.