Even-parity autoionizing states in the extreme-ultraviolet photoabsorption spectra of Mg, Al⁺, and Si²⁺

The dual-laser-produced plasma (DLP) photoabsorption technique has been used to study 2p→3s excitations in the isoelectronic species Mg, Al+, and Si2+ prepared in the excited configuration 2p63s3p. The autoionizing upper states belong to the 2p53s23p even-parity configuration. The versatility of the technique is demonstrated through a careful combination of space- and time-resolved photoabsorption scans. Plasma conditions optimized for the observation of the inaccessible parity regime were successfully reproduced along the isoelectronic sequence of interest. All the observed transitions were interpreted with the help of multiconfigurational atomic structure calculations. In the case of magnesium, the photoabsorption data are compared with the ejected-electron spectra excited by low-energy electron impact of Pejcev et al. [J. Phys. B 10, 2389 (1977)]

Examination of the influence of phenyltrimethylammonium chloride (PTMA) concentration on acetochlor adsorption by modified montmorillonite

The results presented in this paper show an impact of the concentration of the aromatic organic cation on the adsorption of acetochlor on the surface of the organic-modified montmorillonite. Natural montmorillonite from Bogovina (Boljevac municipality, Serbia) was used for organic modification in this experiment. Cation exchange capacity of this montmorillonite (86mmol 100g(-1) of clay) was determined using the methylene blue method. In pretreatment, montmorillonite was modified with NaCl. For the purpose of organic modification, three different concentrations of phenyltrimethylammonium chloride (PTMA) have been selected, based on calculated CEC value: 43mmol 100g(-1) of clay (0.5 CEC), 86mmol 100g(-1) of clay (1 CEC) and 129mmol 100g(-1) of clay (1.5 CEC). The changes in the properties of the inorganic and organic modified montmorillonite were examined using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and batch equilibrium method. Freundlich coefficients show higher uptake of the herbicide by montmorillonite modified with PTMA, compared to inorganic-modified montmorillonite. The results also indicate the influence of the organic cation concentration on the adsorption of the selected herbicide

Influence of the organic complex concentration on adsorption of herbicide in organic modified montmorillonite

This study was undertaken to determine the impact of the organic complex concentration on the adsorption of herbicide (acetochlor) at the surface of the organic modified montmorillonite. In this work, natural montmorillonite from Bogovina (Boljevac municipality, Serbia) was used for organic modification. Cation-exchange capacity of this montmorillonite was determined using a methylene blue method (86mmol/100g of clay). Montmorillonite has been modified first with NaCl and then with hexadecyltrimethylammonium bromide (HDTMA-bromide) organic complex. Saturation of cation exchange capacity (CEC) was 50%, 100%, and 150%. Changes in the properties of the inorganic and organic montmorillonite have been examined using the X-ray diffraction, Fourier transform infrared spectroscopy, and batch equilibrium method. Montmorillonite modified with HDTMA-bromide demonstrated higher uptake of the herbicide, compared to the inorganic montmorillonite. Comparing the values Freundlich coefficients in batch equilibrium method, it can be seen that the adsorption of acetochlor decreased in the series: 0.5 CEC HM > 1 CEC HM > 1.5 CEC HM > NaM

Adsorption of Acetochlor Herbicide on Inorganic- and Organic-Modified Bentonite Monitored by Mid-Infrared Spectroscopy and Batch Adsorption

The results of sorption of acetochlor herbicide with different concentrations (1-15 mu g/mL) in inorganic- and organic-modified bentonite are presented. Acetochlor sorption in both bentonite types was studied by attenuated total reflectance spectroscopy in the mid-infrared region and by batch equilibrium method. Infrared spectroscopy results suggest that the interaction of acetochlor with inorganic (or organic) bentonite takes place by mechanism involving the carbonyl stretching vibration and phenyl ring in the acetochlor molecule. The increase of the acetochlor concentration results in red shift of both corresponding band wavenumbers. Batch adsorption study pointed out more expressed sorption of acetochlor in organic bentonite

Excitation of silver by electron impact

Differential cross sections for electron impact excitation of the 5p state of silver have been measured in conjunction with relativistic distorted-wave calculations

Electron-impact excitation of silver

We measure the differential cross sections (DCSs) for the electron-impact excitation of the combined (two fine-structure levels) resonant 4d105pP1/2,3/22 and 4d95s2D5/22 states in silver from the 4d105sS1/22 ground state. A comparison with the predictions of the relativistic distorted-wave (RDW) approximation model is carried out. Relativistic distorted-wave calculations are performed for each level separately and are combined to compare with the measurements. Both the experimental and theoretical results are obtained at incident electron energies E0 of 10, 20, 40, 60, 80, and 100 eV and scattering angles θ from 10° up to 150° (experiment) and from 0° to 180° (calculations). Absolute values for the experimental DCSs are obtained by normalizing relative DCSs to theoretical RDW results at 40° at all energies except at 10 eV, where we performed the normalization of the relative DCSs at 10° to our previous small-angle experimental DCS values [S. D. Tošić, Nucl. Instrum. Methods Phys. Res. Sect. B 279, 53 (2012)10.1016/j.nimb.2011.10.066]. The integrated cross sections, which include integral QI, momentum transfer QM, and viscosity QV cross sections, are determined by numerical integration of the absolute DCSs

Absolute differential cross sections for electron excitation of silver at small scattering angles

We present results of our experimental and theoretical investigations of the electron excitation of the ground 4d105s state of silver. Differential cross sections (DCSs) for the excitation of the first combined resonant 4d105p state (two fine-structure levels with total angular momentum J = 1/2 and 3/2 which cannot be distinguished in the present experiment) were measured at electron-impact energies (E0) of 10, 20, 40, 60, 80 and 100 eV and for a range of scattering angles (θ) from 3°up to 15°. Absolute DCSs were obtained by the normalization of relative differential cross sections to the optical oscillator strengths. The relativistic distorted wave (RDW) method was used to calculate DCSs and generalized oscillator strengths for each level separately and the combined results are compared with the measurements

Adsorption-desorption behaviour of clomazone in Regosol and Chernozem agricultural soils

Studies of adsorption and desorption of pesticides by soils are important for understanding and predicting their fate and transmission in the environment. Considering the agricultural and environmental relevance of clomazone, its sorption-desorption behaviour was studied in two widespread Serbian agricultural soil types named Regosol and Chernozem. Both phenomena are well-described by the Freundlich equation, which shows that clomazone is generally sorbed more to organic matter than to the mineral soil fractions. Chernozem, a soil containing more of both organic matter and clay, was found to bind more, and desorb less herbicide, than Regosol. Higher desorption hysteresis obtained for Chernozem could be attributed to its larger number of high-energy sorption sites, compared to Regosol. In both soils, the hysteresis effect increases with the rise of initial clomazone concentration in the soil-water system, while the percentage of desorbed amount during successive desorption cycles decreases. The presented adsorption-desorption study shows that soil composition plays an important role in clomazone behaviour and fate in the environment, and a significantly reduced probability of contamination of both the deeper soil layers and groundwater may be expected when this herbicide is found in humus-rich soils

Procedure for the space certification of a controller for soilless cultivation

After a description of soilless cultivations and the presentation of a control system to manage all phases of a greenhouse designed and built for Earth's applications, the article shows a procedure to get the space certification for this kind of system

Absorption effects in intermediate energy elastic electron scattering from xenon

We present experimental and theoretical differential cross sections for elastic electron scattering from xenon. Two independent measurements were carried out at (1) Chungnam National University for incident electron energies of 10, 20, 30, 50 and 100 eV and scattering angles from 10° up to 180° and (2) the Institute of Physics in Belgrade for incident electron energies of 20, 30 and 50 eV and scattering angles from 10° up to 150°. While these latter measurements do not cover the full angular range up to 180°, they still extend somewhat higher in scattering angle than previous measurements. It would appear that the theoretical treatment of intermediate energy elastic scattering from xenon is sensitive to the inclusion of absorption effects, particularly at backward scattering angles. This observation plus the previous results for the case of krypton indicates that the role of absorption is generally quite important for the rare gases