2,4,8,10-Tetraoxa-3,9-diphosphaspiro[5.5]undecane-3,9-disulfide and Some Derived Compounds

2,4,8,10-Tetraoxa-3,9-diphosphaspiro[5.5]undecane-3,9-disulfide (I) has been prepared by the treatment of 3, 9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane (II) with hydrogen sulfide. The reactions of I with thiocyanates to give esters of 3,9-dimercapto-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane-3, 9-disulfide (III) and with isocyanates and isothiocyanates to give P-carbamoyl and thiocarbamoyl derivatives of I were investigated. I was also found to condense with chloral to produce an α-hydroxy-thiophosphonate (XXVIII), but similar reactions with other aldehydes failed to yield analogous products.     

Laser dye stability,part 12. The pyridinium salts

Improved laser output is demonstrated in KrF and XeCl lasers with x-ray preionization. The influence of gas composition, preionization geometry, x-ray dose,E/p value and temporal delay between x-ray pulse and laser discharge is discussed. In XeCl lasing has been achieved with an x-ray dose of 0.2 mR whereas approx. 3 mR are required for KrF. For both systems, the highest output energy and the lowest possibleE/p ratio were observed with Ne buffered gas mixtures. Dissociative attachment to halogen molecules on a ns time scale supported by a relatively slow laser voltage rise is recognized as the main electron loss channel preventing a long lifetime of the preionization electrons. High preionization intensity is thus desirable at the moment of voltage breakdown.     

Cathodoluminescence study of visible luminescence in hydrothermal ZnO crystals

We present a study of the visible luminescence in ZnO hydrothermal crystals. The study is carried out on oxygen polarity basal plane (000-1) plates that are sliced through several distinct growth sectors of the crystal. The plates reveal three distinct regions that display differences in the luminescence emission, especially in the visible range. These differences should be related to the variation in the distribution of impurities and native defects in the various growth sectors of hydrothermal ZnO. CL images also expose the presence of nonradiative recombination centers that are associated with point defects or complexes of point defects. CL measurements varying the acceleration voltage of the e-beam reveal that the deep levels responsible for the green luminescence, and in a minor extension those responsible for the yellow-orange luminescence are depleted near the surface. A discussion about the main hypothesis accounting for such behavior is presented. PACS 71.55.Gs; 71.55.-i; 78.55.Et; 78.60.Hk     

Wire initiation critical for radiation symmetry in z-pinch-driven dynamic hohlraums

Axial symmetry in x-ray radiation of wire-array z pinches is important for the creation of dynamic hohlraums used to compress inertial-confinement-fusion capsules. We present the first evidence that this symmetry is directly correlated with the magnitude of the negative radial electric field along the wire surface. This field (in turn) is inferred to control the initial energy deposition into the wire cores, as well as any current shorting to the return conductor.     

GaAs optical parametric oscillator with circularly polarized and depolarized pump

We demonstrate an optical parametric oscillator (OPO) based on GaAs pumped with linearly polarized and circularly polarized light and show that the relative OPO thresholds agree with theoretical expectations. For the circularly polarized pump, the threshold was as low as for the [111]-linearly polarized pump case. The pump was also passed through a Lyot depolarizer to produce pseudo-depolarized light, and the OPO threshold in this case was only 22% higher than that for [001]-linearly polarized pump.