2,4-Dichlorophenoxyacetic Acid Derived Schiff Base and Its Lanthanide(III) Complexes: Synthesis, Characterization, Spectroscopic Studies, and Plant Growth Activity

2,4-Dichlorophenoxyacetic acid derived Schiff base (HL) and its lanthanide [La(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Dy(III), Y(III)] complexes were synthesized and characterized by various spectroscopic (1H, 13C, DEPT and 2D HMQC NMR, FT-IR, UV-Vis, and mass) techniques and other analytical methods. HL exhibits “E” and “Z” isomerism and was confirmed by variable temperature 1H NMR studies. The spectral and analytical data reveals the bidentate coordination of HL to lanthanide(III) ion, through carboxylic acid group via deprotonation. Fluorescence spectrum of europium complex shows bands at 578, 592, and 612 nm assignable to D05→F07, D05→F17, and D05→F27, respectively. Auxin activity of HL and lanthanum(III) complex on wheat seeds (Triticum durum) was measured at different concentrations. The percentage germination, root length, and shoot length were recorded. An enhancement in the plant growth activity of the ligand was observed on complexation and the best activity was observed at 10−6 M concentration

Measurement of single electron emission in two-phase xenon

We present the first measurements of the electroluminescence response to the emission of single electrons in a two-phase noble gas detector. Single ionization electrons generated in liquid xenon are detected in a thin gas layer during the 31-day background run of the ZEPLIN-II experiment, a two-phase xenon detector for WIMP dark matter searches. Both the pressure dependence and magnitude of the single-electron response are in agreement with previous measurements of electroluminescence yield in xenon. We discuss different photoionization processes as possible cause for the sample of single electrons studied in this work. This observation may have implications for the design and operation of future large-scale two-phase systems.Comment: 11 pages, 6 figure

Design and Performance of the XENON10 Dark Matter Experiment

XENON10 is the first two-phase xenon time projection chamber (TPC) developed within the XENON dark matter search program. The TPC, with an active liquid xenon (LXe) mass of about 14 kg, was installed at the Gran Sasso underground laboratory (LNGS) in Italy, and operated for more than one year, with excellent stability and performance. Results from a dark matter search with XENON10 have been published elsewhere. In this paper, we summarize the design and performance of the detector and its subsystems, based on calibration data using sources of gamma-rays and neutrons as well as background and Monte Carlo simulations data. The results on the detector's energy threshold, energy and position resolution, and overall efficiency show a performance that exceeds design specifications, in view of the very low energy threshold achieved (<10 keVr) and the excellent energy resolution achieved by combining the ionization and scintillation signals, detected simultaneously

A xenon gas purity monitor for EXO

We discuss the design, operation, and calibration of two versions of a xenon gas purity monitor (GPM) developed for the EXO double beta decay program. The devices are sensitive to concentrations of oxygen well below 1 ppb at an ambient gas pressure of one atmosphere or more. The theory of operation of the GPM is discussed along with the interactions of oxygen and other impurities with the GPM's tungsten filament. Lab tests and experiences in commissioning the EXO-200 double beta decay experiment are described. These devices can also be used on other noble gases.Comment: 41 pages, 26 figure

The XENON100 Dark Matter Experiment

The XENON100 dark matter experiment uses liquid xenon (LXe) in a time projection chamber (TPC) to search for Xe nuclear recoils resulting from the scattering of dark matter Weakly Interacting Massive Particles (WIMPs). In this paper we present a detailed description of the detector design and present performance results, as established during the commissioning phase and during the first science runs. The active target of XENON100 contains 62 kg of LXe, surrounded by an LXe veto of 99 kg, both instrumented with photomultiplier tubes (PMTs) operating inside the liquid or in Xe gas. The LXe target and veto are contained in a low-radioactivity stainless steel vessel, embedded in a passive radiation shield. The experiment is installed underground at the Laboratori Nazionali del Gran Sasso (LNGS), Italy and has recently published results from a 100 live-days dark matter search. The ultimate design goal of XENON100 is to achieve a spin-independent WIMP-nucleon scattering cross section sensitivity of \sigma = 2x10^-45 cm^2 for a 100 GeV/c^2 WIMP.Comment: 23 pages, 27 figures; version accepted by journa

Ionization in liquids. Final technical report, November 1, 1993--December 31, 1995

The objective of these studies which began in 1993 was to provide new information on electron and ion transport and reactions in model liquids and biomimetic systems that is pertinent to the roles of charged species in inducing radiobiological damage and to elucidate the interrelationship among the carcinogenicity, mutagenicity and electrophilicity of chemicals. This final report summarizes research efforts in the following areas: electrons in biological systems; and electron and ion transport and reactions in model liquids. In biological systems attention was focused on the following: excess electrons as probes of carcinogen electrophilicity; cost effectiveness of k{sub e} as a carcinogen-screening test; and conversion of k{sub e} to a carcinogen-screening electronic device. In model liquids, research was focused on two areas. The first investigated radiation-induced dimerization of fullerenes. The second area studied radiolytic synthesis of fullerene derivatives

Ionization in liquids. Progress report, September 1, 1977-April 30, 1981

Quasifree electrons simulate the behavior of unsolvated or dry electrons in aqueous media including the special case of biological systems. A model of direct radiosensitization was developed based on dry charge-carriers having an extended lifetime in the sheath of structured water that surrounds polar biomolecules. In this model, the pre-solvation lifetimes of dry electrons increased with an increase in the rotational times of solvent molecules. During the development of this model, an increasing number of radiosensitizers were found to be carcinogenic. Measurement of the k/sub e/'s of known carcinogens and noncarcinogens revealed that carcinogens attached quasifree electrons at diffusion-controlled rates, whereas the k/sub e/'s of noncarcinogens were significantly less. To explore the k/sub e/-carcinogenicity correlation further, a study of quasifree electron attachment to the water pools of reversed micelles was conducted. The degree of structuredness of the water pools which determines the k/sub e/ of the reversed micellar systems was also controlled. Another approach to controlling the microenvironment of quasifree electrons in biological systems was done in studies of radiation-induced damage to DNA in concentrated DNA solutions. The high concentration of DNA introduces more structure into the solutions than that occurring in typical in vitro experiments. The structural enhancement by DNA extends the lifetime of unsolvated charge-carriers. The DNA-damaging effects of radiolyticaly produced charge-carriers were also determined in studies of synergistic mutagenesis in bacteria simultaneously exposed to ionizing radiation and electrophilic chemical carcinogens. The attachment-detachment equilibrium of nicotine in hexane solutions was also studied. Both the kinetics and the thermodynamics of electron reactions were studied. (ERB

Ionization in Liquids [Annual] Progress Report, 1993--1994

Progress in 1993--94 was focused on delineating how ions of the model nonpolar spherical solute Buckminsterfullerene interact differently with various nonpolar solvents than does the ellipsoidal fullerene analog C-70, and exposing a variety of new audiences to the electrophilicity-carcinogenicity relationship in order to obtain fresh insight into this relationship that may lead to elucidation of the role of electrons in carcinogenesis and thereby a better understanding of the biological effects of ionizing radiation. To achieve these goals a new collaboration was established with scientists at Oak Ridge National Lab who have unique facilities to characterize fullerene and its radiolytic products

Ionization in Liquids. Progress Report, November 1, 1990--October 31, 1993

Studies on use of buckminister fullerines as a test subject to understand electron-related processes in radiobiology are described