Development of an ELISA screening test for nitroimidazoles in egg and chicken muscle

An antibody was generated that can bind metronidazole (MNZ), a nitroimidazole drug used in veterinary medicine to treat poultry for coccidiosis and histomoniasis. A direct competitive enzyme-linked immunosorbent assay (cELISA) is described. It was used to characterise binding of this antibody to a number of nitroimidazole drugs. It displayed cross-reactivity with dimetridazole (DMZ), ronidazole (RNZ), hydroxydimetridazole (DMZOH), and ipronidazole (IPZ).

Rapid forensic analysis and identification of "lilac" architectural finishes using Raman spectroscopy

The potential of Raman spectroscopy to discriminate between architectural finishes (household paint) has been investigated using a test set of 51

Spectroscopy of astrophysical plasmas in the laboratory

Most of the matter in the universe is in the few form of a plasma. Over the past years physicists have produced laboratory plasmas that can mimic those observed in astrophysics. The best known is probably the tokamak, which has similar physical conditions and plasma processes to those found in collisionally dominated solar and stellar transition regions and coronae. Spectroscopy of such laboratory plasmas, in, particular at, ultraviolet and X-ray wavelengths, has greatly aided our understanding of their astrophysical counterparts. More recently, experiments have been performed on the Z Machine at the Sandia National Laboratory in the USA with the aim of creating, for the first time, steady-state photoionization-dominated plasmas that recreate the conditions found in some accretion-powered X-ray sources, such as X-ray binaries. In the future, experiments are envisaged with laser-produced plasmas at AWE Aldermaston that may be able to mimic the steady-state conditions found in high-energy accretion-powered sources, including the central regions of active galaxies.

Laser-Induced Fluorescence Measurements of Absolute Atomic Densities: Concepts and Limitations

The potential of laser-induced fluorescence spectroscopy of atoms is reviewed with emphasis on the determination of absolute densities. Examples of experiments with single-photon and two-photon excitation are presented. Calibration methods applicable with the different schemes are discussed. A new method is presented that has the potential to allow absolute measurement in plasmas of elevated pressure where collisional depletion of the excited state is present.

Measurement of Quenching Coefficients and Developement of Calibration Methods for Quantitative Spectroscopy of Plasma at Elevated Pressures

Measurements of collisional de-excitation (quenching) coefficients required for the interpretation of emission and fluorescence spectroscopic measurements are reported. Particular attention is turned on argon transitions which are of interest for actinometric determinations of atomic ground state populations and on fluorescence lines originating from excited atoms and noble gases in connection with two-photon excitation (TALIF) of atomic radicals. A novel method is described which allows to infer quenching coefficients for collisions with molecular hydrogen of noble gas states in the energy range up to 24 eV. The excitation is performed in these experiments by collisions of energetic electrons in the sheath of an RF excited hydrogen plasma during the field reversal phase which lasts about 10 ns. We describe in addition a calibration method - including quenching effects - for the determination by TALIF of absolute atomic radical densities of hydrogen, nitrogen and oxygen using two-photon resonances in noble gases close by the resonances of the species mentioned. The paper closes with first ideas on a novel technique to bypass quenching effects in TALIF by introducing an additional, controllable loss by photoionization that will allow quenching-free determination of absolute atomic densities with prevalent nanosecond laser systems in situations where collisional de-excitation dominates over spontaneous emission.

First dielectronic recombination measurements with H-like uranium

In this report we show first results on dielectronic recombination (DR) measurements with H-like uranium U91+. The experiments were conducted at the heavy ion storage ring ESR of GSI. The electron cooler of the ESR was used as a target for free electrons. Stochastic pre-cooling of the stored ion beam was employed in order to accomplish high-energy resolution at the necessary high electron-ion collision energies of more than 64 keV. For the DR of U91+ this novel technique enabled us to measure for the first time the KLL-DR process and even to resolve the individual j-j' fine structure components of the KLjLj' resonances. The experimental data are compared with fully relativistic Multi-Configuration Dirac-Fock (DR-MCDF) calculations. (c) 2006 Elsevier Ltd. All rights reserved.

An experiment for two-color photoionization using high intensity extreme-UNT free electron and near-IR laser pulses

We describe an experimental system designed for single-shot photoelectron spectroscopy on free atoms and molecules at the Free Electron Laser in Hamburg (FLASH at DESY). The combination of the extreme ultra-violet (EUV) Free Electron Laser and a temporally synchronized optical fs laser (Ti:Sapphire) enables a variety of two-color pump-probe experiments. The spectral, temporal and spatial characteristics of both the EUV FEL and the optical laser pulses, the experimental procedure to control their overlap as well as the performance of an electron spectrometer used to obtain single-shot photoelectron spectra are discussed. As an illustration of the capabilities of this set-up, some results on two-photon two-color ionization of rare gases are presented. (c) 2007 Elsevier B.V. All rights reserved.

Measurements of the XUV transmission of aluminium with a soft x-ray laser

We have used XUV lasers to make absolute measurements of the photoabsorption coefficient of Al at energies just below that of the L3 absorption edge at 72.7 eV. Transmission measurements at photon energies of 53.7 and 63.3 eV have been made using Ne-like Ni and Ge XUV lasers. The XUV laser output was recorded in first and second orders using a flat-field spectrometer. Al foils with steps of various thicknesses were placed over the first order diffracted signal, while the second order diffraction was used to monitor the beam profile at each position. The transmission data agree extremely well with the original measurements at these wavelengths made by Henke and co-workers (Henke B L, Gullikson E M and Davis J C 1993 At. Data Nucl. Data Tables 54 18 1), but are in conflict with subsequent measurements which are currently in common use (Gullikson E M, Denham P, Mrowka S and Underwood J H 1994 Phys. Rev. B 49 16 283). The exact values of the absorption coefficients in this region of the spectrum have significant implications for the diagnosis of the energy and intensity output of XUV lasers.

Generation of a transient short pulse X-ray laser using a traveling-wave sub-ps pump pulse

This paper summarises die main results obtained during the two experimental campaigns on TCE X-ray lasers that we have carried out since the last Kyoto X-ray laser Conference in 1998. A two-color (2 omega /1 omega) pumping configuration was tested and led to the observation of a strong lasing line at 16 nm, identified to a 4f-4d transition in Ni-like Ag. A strong x 300-400 enhancement of the 13.9 nm Ni-like 4d-4p lasing emission was obtained when a traveling wave short pulse pumping was applied. Finally the temporal history of the 13.9 nm laser pulse was measured with a high-resolution Streak camera, A very short 2 ps X-ray laser pulse was directly demonstrated for the first time.

Temporal resolution of a transient pumping X-ray laser

We report on a time-resolved study of a Ni-like transient collisionnal X-ray laser with a resolution as high as 1.9 ps The FWHM duration of the Ni-like x-ray laser pulse at 13.99 nin Ag J = 0 -->1 4d-4p line is measured to be as short as similar to2 ps at optimum conditions of pump laser irradiation. This is about four times shorter than was estimated in previous experiments. The x-ray laser signal appears in the rising edge of the continuum emission. The x-ray laser duration rises significantly when the short (heating) pulse duration is increased and when doubling the peak-to-peak delay of the two irradiation pulses, It does not change when the short pulse energy is increased. The results presented are the first direct measurements of the temporal profile of the x-ray laser output at a high resolution.

Developments in X-ray laser pumping with travelling wave at Vulcan

Saturated output has been observed for both Ne and Ni-like X-ray lasers when Pumped in the transient mode. As these 'normal' transitions display very high gain, attempts have been made to observe a 2p --> 2s inner shell transition in Ne-like ions, which scale well towards the water window. Modelling of the pump conditions for Ge lasing at 6.2 run is presented. As the predicted gain is low the experiment was set up for 18 mm targets. Shots were taken on Ti, Fe, Ni and Ge. A similar to1.5 ps travelling wave pulse is applied at various times after the peak of a long, preforming Pulse. Various pump conditions were attempted but no inner shell X-ray laser was detected.

Ionography of Submicron Foils and Nanostructures Using Ion Flow Generated in FS-Laser Cluster Plasma

A novel type of submicron ion radiography designed to image low-contrast objects, including nanofoils, membranes and biological structures, is proposed. It is based on femtosecond-laser-driven-cluster- plasma source of multicharged ions and polymer dosimeter film CR-39. The intense isotropic ion flow was produced by femtosecond Ti:Sa laser pulses with intensity similar to 4x10(17) W/cm(2) absorbed in the supersonic jet of the mixed He and CO2 gases. Two Focusing Spectrometers with Spatial Resolution (FSSR) were used to measure X-ray spectra of H-and He-like multicharged oxygen ions. The spectra testify that ions with energy more than 300 keV were radiated in different directions from the plasma source. High contrast ion radiography images were obtained for 2000 dpi metal mesh, 1 mu m polypropylene and 100 nm Zr foils as well as for the different biological objects. Images were recorded on a 1 mm thick CR-39 detector, placed in contact with back surface of the imaged samples at the distances 140 -160 mm from the ion source. The spatial resolution of the image no worse than 600 nm was provided. A difference in object thickness of 100 nm was very well resolved for both Zr and polymer foils. The ion radiography images recorded at different angles from the source, demonstrated almost uniform spatial distribution of ion with total number of 10(8) per shot. (C) 2009 WILEY-VCH Vertag GmbH & Co. KGaA, Weinheim

Dielectronic recombination in He-like, Li-like, and Be-like highly charged ions in the KLL and KLM manifolds

This paper reports a systematic study of the dependence on atomic number of the dielectronic recombination resonance strengths for He-like, Li-like and Be-like ions. Recent measurements of dielectronic recombination resonance strengths for the KLL and KLM manifolds for iron, yttrium, iodine, holmium, and bismuth are also described. The resonance strengths were normalized to calculated electron impact ionization cross sections. The measured resonance strengths generally agree well with theoretical calculations using the distorted wave approximation. However, KLM resonance strength measurements on high atomic number open-shell ions gave higher values than those suggested by calculations. Using recently measured data, along with existing results, scaling laws have been generated as a function of atomic number for He-like, Li-like, and Be-like ions in the KLL and KLM manifolds.

Ion acceleration from the shock front induced by hole boring in ultraintense laser-plasma interactions

Ion-acceleration processes have been studied in ultraintense laser plasma interactions for normal incidence irradiation of solid deuterated targets via neutron spectroscopy. The experimental neutron spectra strongly suggest that the ions are preferentially accelerated radially, rather than into the bulk of the material from three-dimensional Monte Carlo fitting of the neutron spectra. Although the laser system has a 10(-7) contrast ratio, a two-dimensional magnetic hydrodynamics simulation shows that the laser pedestal generates a 10 mum scale length in the coronal plasma with a 3 mum scale-length plasma near the critical density. Two-dimensional particle-in-cell simulations, incorporating this realistic density profile, indicate that the acceleration of the ions is caused by a collisionless shock formation. This has implications for modeling energy transport in solid is caused by a collisionless shock formation. This has implications for modeling energy transport in solid density plasmas as well as cone-focused fast ignition using the next generation PW lasers currently under construction.