A Raman and infrared spectroscopic study of Ca2+ dominant members of the mixite group from the Czech Republic

The minerals of the mixite group—zálesíite CaCu₆[(AsO₄)₂(AsO₃OH)(OH)₆]·3H₂O from abandoned uranium deposit Zálesí, Czech Republic and calciopetersite CaCu₆[(PO₄)₂(PO₃OH)(OH)₆]·3H₂O from a quarry near Domašov na Bystřicí, northern Moravia, Czech Republic—were studied by Raman and infrared spectroscopy. The observed bands were assigned to the stretching and bending vibrations of (AsO₄)³⁻ and (AsO₃OH)²⁻ ions in zálesíite, and (PO₄)³⁻ and (PO₃OH)²⁻ in calciopetersite, and to molecular water, hydroxyl ions, and Cu‐(O,OH) units in both minerals. O H···O hydrogen‐bond lengths in zálesíite and calciopetersite structures were calculated with Libowitzky's empirical relation. Copyright © 2010 John Wiley & Sons, Ltd.     

Diffusion of 99-technetium in compacted bentonite under aerobic and anaerobic conditions

The main aim of this study was to investigate diffusion of technetium ⁹⁹Tc under different conditions. Because technetium represents one of the most dangerous fission products due to its very long halftime and high mobility in aerobic conditions diffusion experiments of technetium (as ⁹⁹TcO ₄ ⁻ anion) in Czech bentonite from Rokle locality have been carried out. For performance and evaluation of experiments the through-diffusion method was chosen and apparent (D_a) and effective (D_e) diffusion coefficients were evaluated. The effects of particle mesh-size, dry bulk density and aerobic or anaerobic conditions on diffusion were studied. In the presence of oxygen, technetium occurs in oxidation state VII, as an anion, soluble and mobile in the environment. However, under reducing conditions it occurs in a lower oxidation states, mainly as insoluble oxides or hydroxides. Aerobic experiments were carried out under laboratory conditions and anaerobic experiments were performed in a nitrogen atmosphere in a glove box, to simulate the real underground conditions.     

Determination of titanium content in pyrope by Raman spectroscopy

The titanium content of pyrope garnet can be quantified using the intensity of a Raman band at about 830 cm⁻¹ that is normalized to the 363 cm⁻¹ band using a spectrometer‐specific calibration using 10 to 15 chromian pyropes from Bohemia, Czech Republic. An accuracy of 0.025 wt% could be achieved for TiO₂ contents between 0.17 and 0.67 wt% TiO₂ with a Raman spectrometer with a spectral resolution of better than 3.9 cm⁻¹. The technique can be used in petrological and gemmological studies. Copyright © 2015 John Wiley & Sons, Ltd.     

A CCD based detector for quick detection of pressure induced phase transitions

Abstract

A high sensitivity CCD based two dimensional angle dispersive X-ray are a detector has been developed for quick detection of pressure induced phase transitions for a laboratory X-ray source such as a rotating anode generator. The performance of this detector was tested by successfully carrying out powder X-ray diffraction measurements on element Pd, intermetallics AuIn², AuGa² and low Z scatterer adamantane (C₁₀H_l6) at ambient conditions. Its utility for quick detection of phase transitions at high pressures with diamond anvil cell (DAC) is demonstrated by reproducing the known pressure induced structural phase transitions in RbI and KI. The importance of this detector system in search of unknown phase transitions has been established by observing new structural phase transitions in In_0.25Sn_0.75 and AuGa₂. Various softwares have also been developed such as interactive location of centre of diffraction rings, radial integration and image enhancement to analyze data from this detector.     

Electronic Emission from Hg-Atoms and HgCl-Radicals Due to Collisions of Nitrogen Ions and HgCl2/Hg2Cl2 Molecules

Emission spectra of the (B-X), (C-X) and (D-X) band systems of HgCl-radical and mercury atomic lines from highly excited levels to various lower levels have been observed during collisions of N⁺ and N⁺ ₂ ions and HgCl₂/Hg₂Cl₂ molecules at different laboratory kinetic energies of the projectile ions. Emission cross-sections of the most intense mercury atomic lines and the (C-X) band system of the HgCl-radicals, have been measured in the laboratory kinetic energy range of 100–900 eV.     

30 years of production of highly enriched nitrogen-15 in the GDR

Almost 30 years ago, the stable isotope ¹⁵N had covered a wide field of application in science and technology. With the preparation of the first smaller amounts of ¹⁵N in 1958, an intensive work of research and development started for the production, analysis, and application of ¹⁵N in the GDR. In this publication, activities of research and development for ¹⁵N production using the principle of chemical exchange in the system NO _x /HNO₃ from a laboratory scale to the introduction into chemical industry are described and new projects reported.     

Stable carbon isotopes in dissolved inorganic carbon: extraction and implications for quantifying the contributions from silicate and carbonate weathering in the Krishna River system during peak discharge

We present a comparative study of two offline methods, a newly developed method and an existing one, for the measurement of the stable carbon isotopic composition (δ¹³C) of dissolved inorganic carbon (DIC; δ¹³C_DIC) in natural waters. The measured δ¹³C_DIC values of different water samples, prepared from laboratory Na₂CO₃, ground and oceanic waters, and a laboratory carbonate isotope standard, are found to be accurate and reproducible to within 0.5 ‰\ (1σ). The extraction of CO₂ from water samples by these methods does not require pre-treatment or sample poisoning and can be applied to a variety of natural waters to address carbon cycling in the hydrosphere. In addition, we present a simple method (based on a two-end-member mixing model) to estimate the silicate-weathering contribution to DIC in a river system by using the concentration of DIC and its δ¹³C. This approach is tested with data from the Krishna River system as a case study, thereby quantifying the contribution of silicate and carbonate weathering to DIC, particularly during peak discharge.     

New bound to the probability of 76Ge ββ decay to the 0 1 + 76Se level

Measurements were carried out at the underground low-background laboratory of the Baksan Neutrino Observatory using a detection system involving four ultrapure germanium detectors made from enriched ⁷⁶Ge. The sensitivity of the experiment to the detection of a ⁷⁶Ge double beta decay to the excited levels of the ⁷⁶Se nucleus was determined. As a result of 228-day measurements, the new bound to the time of ⁷⁶Ge half-decay to the ⁷⁶Se 0 ₁ ⁺ excited level is found to be T _1/2(2ν2β)≥6.2×10²¹ years (90% confidence level).     

Chirped laser dispersion spectroscopy with harmonic detection of molecular spectra

Chirped laser dispersion spectroscopy (CLaDS) has been introduced recently as a technique that performs molecular detection based on measurement of optical dispersion. In this paper, a new detection scheme based on chirp modulation (CM) and subsequent phase-sensitive detection is described. CM-CLaDS inherits the full advantages of conventional CLaDS and additionally overcomes some of its limitations. A prototype CM-CLaDS instrument has been developed and characterized in laboratory conditions. The system is based on a distributed feedback quantum cascade laser which operates around 4.52???m and can probe the most intense nitrous oxide (N₂O) ro-vibrational transitions. Preliminary performance tests are presented and provide a path/bandwidth normalized minimum N₂O detection limit below 100?ppbv?m/Hz^1/2.     

Spectroscopic studies on vanadyl ion in rubidium magnesium sulphate hexahydrate

The optical absorption spectrum of VO²⁺ ion in a single crystal of Rb₂Mg(SO₄)₂6H₂O has been investigated both at laboratory and liquid nitrogen temperatures. The electron paramagnetic resonance (EPR) spectrum of the polycrystalline sample has also been investigated at the laboratory temperature. Both optical absorption and EPR spectra are characteristic of the VO²⁺ ion in tetragonal symmetry. Molecular orbital coefficients have been evaluated by correlating the optical absorption and EPR data.     

2.5-MeV neutron source controlled by high-intensity pulsed laser generating plasma

A laptop neutron source suited for the most demanding field or laboratory applications is presented. It is based on laser ablation of CD₂ primary targets, plasma acceleration of the D⁺ ions, and their irradiation of secondary CD₂ targets. The deuterium–deuterium (D-D) fusion reaction is induced in the secondary target, according to the values of fusion cross-section versus deuteron energy, which show a significant probability also at relatively low ion energies. The experiments were completed in the PALS laboratory, Prague, detecting monoenergetic neutrons at 2.45 MeV with an emission flux of about 10⁹ neutrons per laser shot. Other experiments demonstrating the possibility to induce D-D events were performed at IPPLM, Warsaw, and at INFN-LNS, Catania, where the deuterons were accelerated at about 4 MeV and 50 keV, respectively. In the last case, a low laser intensity and a post-ion acceleration system were employed. A special interaction chamber, under vacuum, is proposed to develop a new source of monochromatic neutrons or thermalized distribution of neutrons     

用夸克模型探索π-N相互作用

本文中用夸克模型,Warke近似,并作为补偿,在夸克唯象势中加入中程势(-1)^T+JKre^(-r/a₂),计算了π-N相互作用势,从此势计算了L_2T,2J=S₁₁,S₃₁,P₁₁,P₃₁,P₁₃和P₃₃六种道的相移。在入射π介子动能E_π^k(lab)=0—700MeV范围内,与由实验方法决定的相移进行了比较。 关键词：     

Raman spectroscopic study of the phosphate mineral churchite‐(Y) YPO4·2H2O

Raman spectroscopy has been used to study the rare‐earth mineral churchite‐(Y) of formula (Y,REE)(PO₄) ·2H₂O, where rare‐earth element (REE) is a rare‐earth element. The mineral contains yttrium and, depending on the locality, a range of rare‐earth metals. The Raman spectra of two churchite‐(Y) mineral samples from Jáchymov and Medvědín in the Czech Republic were compared with the Raman spectra of churchite‐(Y) downloaded from the RRUFF data base. The Raman spectra of churchite‐(Y) are characterized by an intense sharp band at 975 cm⁻¹ assigned to the ν₁ (PO₄³⁻) symmetric stretching mode. A lower intensity band observed at around 1065 cm⁻¹ is attributed to the ν₃ (PO₄³⁻) antisymmetric stretching mode. The (PO₄³⁻) bending modes are observed at 497 cm⁻¹ (ν₂) and 563 cm⁻¹ (ν₄). Some small differences in the band positions between the four churchite‐(Y) samples from four different localities were found. These differences may be ascribed to the different compositions of the churchite‐(Y) minerals. Copyright © 2009 John Wiley & Sons, Ltd.     

标定粉末照相指数的一个新图解法

本文叙述了标定德拜-谢乐照相指数的一个新图解法。利用三条低角度衍射线的sin²θ值和该晶体的密度,在A-C空间画一系列条件直线及等原子曲线。三条条件直线和一条等原子曲线的交点直接决定了晶胞的大小和晶胞内所含的原子数或位形单位数。这个方法可应用于四方晶系和六角晶系。 关键词：     

Diode laser measurements of air and nitrogen broadening in the ν2 bands of HDO,H216O,and H218O

Pressure-broadening coefficients for several rotation-vibration lines in the ν₂ bands of HDO, H₂¹⁶O, and H₂¹⁸O have been determined from laboratory spectra recorded in the 1260- to 1360-cm⁻¹ region with a tunable diode laser spectrometer system. Air and nitrogen were used as the broadening gases and, for all the measured transitions, the nitrogen-broadened half-widths were found to be consistently larger than the corresponding air-broadened half-widths by about 12%. The results have been compared to previously published values when appropriate.     

Elastic scattering and break-up processes in then-d system

A method to solve the AGS equations in momentum space is presented. The two-nucleon transition operators are generated with the new Bonn potential restricted to the states¹ S ₀,³ S ₁-³ D ₁,³ P ₀,¹ P ₁,³ P ₁,³ P ₂-³ F ₂,¹ D ₂ and³ D ₂. Cross sections and analyzing powers for elastic and break-up processes are calculated at a neutron laboratory energyE _n =10.3 MeV.     

Advances in the Development of Chemical Oxygen-iodine Laser

Results of three problems investigated on a Chemical Oxygen-Iodine Laser (COIL) in our laboratory are presented in connection with the advanced COIL development in the world. These problems concern: i) A gain modulation on the laser transition in iodine atom, I(²P_1/2) - (²P_3/2), by external magnetic field, and its utilization for a COIL output power stabilization, ii) An evaluation of the Einstein A-coefficient of singlet oxygen, O₂(¹ _g), and its utilization in advanced diagnostics for O₂(¹ _g) determination in COIL operation, iii) A chemically driven iodine atom delivery system for advanced COIL.     

Separating Structure and Dynamics in CSA/DD Cross-Correlated Relaxation: A Case Study on Trehalose and Ubiquitin

We present two new sensitivity enhanced gradient NMR experiments for measuring interference effects between chemical shift anisotropy (CSA) and dipolar coupling interactions in a scalar coupled two-spin system in both the laboratory and rotating frames. We apply these methods for quantitative measurement of longitudinal and transverse cross-correlation rates involving interference of ¹³C CSA and ¹³C–¹H dipolar coupling in a disaccharide, α,α- -trehalose, at natural abundance of ¹³C as well as interference of amide ¹⁵N CSA and ¹⁵N–¹H dipolar coupling in uniformly ¹⁵N-labeled ubiquitin. We demonstrate that the standard heteronuclear T₁, T₂, and steady-state NOE autocorrelation experiments augmented by cross-correlation measurements provide sufficient experimental data to quantitatively separate the structural and dynamic contributions to these relaxation rates when the simplifying assumptions of isotropic overall tumbling and an axially symmetric chemical shift tensor are valid.     

Revised and extended analysis of Br VI

The spectrum of five times ionized bromine (Br VI) has been studied in the 150–2060 Å wavelength region. The spectrum was recorded on a 3-m normal incidence vacuum spectrograph at the Antigonish laboratory (Canada) and 6.65-m grazing incidence spectrograph at the Zeeman laboratory (Amsterdam) using a triggered spark light source. The ground configuration of Br VI is 3d¹⁰4s² and the excited configurations 3d¹⁰4s (4p+5p+6p+7p+4f+5f)+3d¹⁰4p4d+3d¹⁰4p5s in the odd parity system and 3d¹⁰4s (4d+5d+6d+5s+6s+7s+8s+5g+6g)+3d¹⁰4p² in the even parity system have been studied. Relativistic Hartree–Fock (HFR) and least squares fitted (LSF) parametric calculations were used to interpret the observed spectrum. Sixty-eight levels of Br VI have now been established, out of which 28 are new levels. Two previously reported levels viz. 4p4d ¹D₂ and ³F₄ were revised. Among one hundred and fifty-eight spectral lines, 69 are newly classified. The accuracy of our wavelength measurements for sharp and unblended lines is ±0.005 Å. The value of the ionization potential has been determined as 704850±200 cm^?1 (87.390±0.025 eV).