Analysis of extreme ultraviolet radiation and hydrodynamics simulation at the core of laser-produced nickel plasmas.

The non-uniformity and transient nature of laser-produced plasma are critical factors that affect the analysis of the extreme ultraviolet spectra of highly charged ions and the diagnosis of plasma states. This paper systematically investigates the characteristics of extreme ultraviolet radiation and the hydrodynamic evolution of laser-produced nickel plasmas from two perspectives: high-spatio-temporal-resolution extreme-ultraviolet spectroscopic measurement and radiation hydrodynamics simulation. The consistency between the four-band experimental spectra and their theoretically simulated spectra confirms the accuracy of the atomic structure parameters and plasma state parameters. We also analyze the significant contribution of the 3d-4f double-excited state radiation to the spectral profile and discuss the influence of the self-absorption caused by plasma opacity on the characteristics of extreme ultraviolet radiation. The findings are crucial for accurately understanding the characteristics of extreme ultraviolet radiation, the hydrodynamic evolution, and the application of medium- and high-Z laser-produced plasma as a pulsed short-wavelength light source.

Pulse high energy Fe: ZnSe laser pumped by Q-switched Er: YAG laser.

We report a pulse Fe: ZnSe laser pumped by an optical chopper Q-switched Er: YAG laser. By analyzed the spatial and temporal match of the gain and chopper, the maximum energy of the optical chopper Q-switched Er: YAG laser is 31mJ with the pulse width of 165 ns. By employing this Er: YAG laser as pump laser of Fe: ZnSe crystal, the maximum output energy of Fe: ZnSe laser is 10mJ with the pulse width of 80 ns at room temperature, that is the maximum energy of Fe: ZnSe laser at this Q-switched system to the best of our knowledge. We also study the directly Q-switched Fe: ZnSe laser, and the 2.7mJ mid-infrared laser with the pulse width of 200 ns is obtained at 80 K.

Pulse operation of linearly polarized diode-pumped cesium-vapor laser based on acousto-optical modulation.

We present a pulse linearly polarized diode-pumped cesium-vapor laser (Cs-DPAL) based on an acousto-optical modulator (AOM) for the first time. The continuous wave (CW) performance of the Cs-DPAL was first investigated, and ~1.05 W linearly polarized CW laser was obtained. Next, we applied a rectangular signal to modulate the AOM. The Cs-DPAL realized a pulse laser output with a maximum repetition rate of 1 MHz and minimum pulse duration of 238 ns. To the best of our knowledge, this is the highest repetition rate reported thus far for a diode-pumped alkali-vapor laser (DPAL). The maximum output power of the pulse laser reached ~0.20 W, and the corresponding Mx 2 and My 2 factors were 1.31 and 1.19, respectively. Finally, we realized code modulation of the Cs-DPAL, with a maximum bit rate of 2 Mb/s.

Theoretical modeling and analysis on the absorption cross section of the two-photon excitation in Rb.

The cross-section is crucial for quantitative characterization and analysis of the absorption process. A model on the absorption cross-section of the simultaneous two-photon excitation in Rb-vapor four-wave mixing process is established by using the coupled-wave equation. Taken into account of the hyperfine structures for 85Rb and 87Rb, the third-order susceptibility and hyperfine line strength are calculated respectively. Then, the influences of hyperfine transition on cross section are investigated and simulation results agree well with the experiment results. The calculated results suggest that high pumping power intensity is essential in Rb two-photon excitation, while narrow linewidth is the limiting factor of high absorption efficiency by comparing normalized absorption profile between pumping beam and two-photon excitation process. Additionally, two approaches to improving absorption efficiency, linewidth narrowness of the pumping beam and absorption linewidth broadening, are proposed.

Stability and Hydrocarbon/Fluorocarbon Sorption of a Metal-Organic Framework with Fluorinated Channels.

The stabilities and hydrocarbon/fluorocarbon sorption properties of a zeolite-like metal-organic framework (MOF) Zn(hfipbb) with fluorinated channels has been studied. By the combination of thermogravimetric analysis (TGA) and powder X-ray diffraction (PXRD) measurements, we confirm that Zn(hfipbb) has exceptionally high hydrothermal and thermal stabilities. The adsorption behaviors of water and methanol by Zn(hfipbb) indicate that it is highly hydrophobic but with high adsorption of alcohols. Hexane and perfluorohexane adsorption measurements show that the fluorinated channels in Zn(hfipbb) have high affinity with hydrocarbon and fluorocarbon. The high fluorophilic nature of the channels and the high stability of the compound suggest its potential utility in practical separation applications.

Computer modeling and experimental study of non-chain pulsed electric-discharge DF laser.

Computer simulation and experimental study of a pulsed electrical-discharge DF laser pumped by the SF(6)-D(2) non-chain reaction are presented. The computer model encompassing 28 reactions is based on laser rate equations theory, and applied to approximately describe the chemical processes of non-chain DF laser. A comprehensive study of the dependence of number density on time for all particles in the gain area is conducted by numerical calculation adopting Runge-Kutta method. The output performance of non-chain pulsed DF laser as a function of the output mirror reflectivity and the mixture ratio are analyzed. The calculation results are compared with experimental data, showing good agreement with each other. Both the theoretical analysis and experimental results present that the laser output performance can be improved by optimizing the mixture ratio and output mirror reflectivity. The optimum values of mixture ratio and output mirror reflectivity are respectively 10:1 and 30%. The single pulse energy of 4.95J, pulse duration of 148.8ns and peak power of 33.27 MW are achieved under the optimum conditions.

Spatial distribution, electron microscopy analysis of titanium and its correlation to heavy metals: occurrence and sources of titanium nanomaterials in surface sediments from Xiamen Bay, China.

Titanium nanomaterials are likely to sink into sediments in substantial quantities due to their wide use in a number of applications for decades. To assess the potential environmental consequences, a better understanding is required of the occurrence and sources of titanium (Ti) nanomaterials in sediments. In this research, we provide the first report of the Ti concentrations and the morphology and composition of Ti-based solids in surface sediments from Xiamen Bay, China. Results indicated that the anthropogenic Ti concentrations in the surface sediments from Xiamen Bay reached approximately 2.74 g kg(-1). Ti nanomaterials could be found in sediments with elevated Ti concentrations, which were often aggregated to a few hundred nanometers (<300 nm) and were composed of several spherical particles, less than 50 nm in size, that were made solely of TiO(x). However, Ti particles (approx. 300-700 nm) could be also found in sediments with lower Ti concentrations, which were presumably components of the natural clay mineral kaolinite. Ti nanomaterials could be easily distributed in sediments associated with elevated levels of organic matter and preferentially attach to those sediments with elevated fine fractions. As a sentinel, or tracer, for other nanomaterials, the field-scale investigation of Ti nanomaterials would contribute to increasing our knowledge on the behavior of engineered nanomaterials in an aquatic environment.

Concentrations of some heavy metals in water, suspended solids, and biota species from Maluan Bay, China and their environmental significance.

Concentrations of heavy metals (Cu, Zn, Cd, and Pb) in surface water (including total recoverable, dissolved, suspended solids) and in aufwuchs encrusted on Moerella iridescens Benson from seven selected sites and two reference sites in Maluan Bay were investigated in order to understand current metal contamination due to industrialization and urbanization in Xiamen, China. The muscle tissues of the study species (Penceus penicillatus, Scylla serrata Forskal, Harengula zunasi Bleeker, Tillapia nilotica) from a trawling area within Maluan Bay were also analyzed in order to evaluate its safety as seafood. Based on the obtained data, metal concentrations in surface water were compared with Marine Seawater Quality Standards of China and the US EPA acute and chronic criteria, which showed that Maluan Bay may be subjected to different levels of contamination by the metals. Metal concentrations under study in the edible parts (muscle) of the investigated biota species were within the safety permissible levels for human consumption. Through Pearson's correlation analysis, the relationships between metal concentrations in surface water and in M. iridescens were evaluated. Copper concentrations in M. iridescens were more strongly positively correlated with particulate copper in suspended solids and total recoverable copper in water rather than with dissolved copper at the sampling sites. The data suggested that copper-rich suspended solids contributed substantially to copper accumulation by M. iridescens and played a critical role in the pathway of copper into the food chain. The conclusions of this investigation are likely to be applicable to other relevant scenarios.

Effects of titania nanoparticles on phosphorus fractions and its release in resuspended sediments under UV irradiation.

Little is known about the effects of nano-TiO(2) on the transformation and transport of phosphorus (P) in resuspended sediments. Chemical sequential extraction was used to investigate P fractions and its release in resuspended sediments under the influence of nano-TiO(2) and UV irradiation. The results showed that the contents of sediment P in all fractions decreased with increasing nano-TiO(2) concentration in UV irradiation, while increased in the dark controls. Furthermore, P release from all fractions was greater in UV irradiation than in the controls. Elevated concentrations (10-50 mg L(-1)) of nano-TiO(2) in UV irradiation significantly facilitated the release of P from organic and Fe oxide fractions, possibly resulting from the partial photo-degradation of organic matter and photochemical transformation of Fe oxides. Apparently, nano-TiO(2) in UV irradiation did not immobilize the loosely sorbed P and reductant soluble P release from the resuspended sediments, possible because (1) some of P released from those fractions were refurnished by the P released from OM; (2) photocatalysis of nano-TiO(2) reduced binding capacity of the resuspended sediments. Our results suggest that the photocatalysis of nano-TiO(2) may offer the potential to regulate the transformation and transport of sediment P in the aquatic environment.