Determination of rhodium in water samples using cloud point extraction (CPE) coupled with flame atomic absorption spectrometry (FAAS)

Cloud point extraction was applied as a method for preconcentration of rhodium after formation of a complex with 2-propylpiperidine-1-carbodithioate (2-PPC), and later determined by flame atomic absorption spectrometry using TritonX-114 as surfactant. Rhodium was complexed with 2-PPC in an aqueous phase and kept for 15 min in a thermostatted bath at 40 °C. Separation of the two phases was accomplished by centrifugation for 15 min at 4000 rpm. The chemical variables affecting the cloud point extraction were optimized and successfully applied to rhodium determination in various water samples. Under optimized conditions, the preconcentration system (100 mL sample) permitted an enhancement factor of 50. The detection limits obtained under optimal conditions was 0.052 ng mL⁻¹. The extraction efficiency was investigated at different rhodium concentrations (7.0–42.0 μg mL⁻¹), and good recoveries (96.42–99.14%) were obtained using this method. It has been applied to the determination of rhodium in water and was compared with reported methods in terms of Student’s ‘t’-test and variance ratio ‘f’-test.     

Effect of annealing temperature on the electrical properties of Au/Ta2O5/n-GaN metal–insulator–semiconductor (MIS) structure

We report on the effect of an annealing temperature on the electrical properties of Au/Ta₂O₅/n-GaN metal–insulator–semiconductor (MIS) structure by current–voltage (I–V) and capacitance–voltage (C–V) measurements. The measured Schottky barrier height (Φ _bo) and ideality factor n values of the as-deposited Au/Ta₂O₅/n-GaN MIS structure are 0.93 eV (I–V) and 1.19. The barrier height (BH) increases to 1.03 eV and ideality factor decreases to 1.13 upon annealing at 500 ^°C for 1 min under nitrogen ambient. When the contact is annealed at 600 ^°C, the barrier height decreases and the ideality factor increases to 0.99 eV and 1.15. The barrier heights obtained from the C–V measurements are higher than those obtained from I–V measurements, and this indicates the existence of spatial inhomogeneity at the interface. Cheung’s functions are also used to calculate the barrier height (Φ _bo), ideality factor (n), and series resistance (R _s ) of the Au/Ta₂O₅/n-GaN MIS structure. Investigations reveal that the Schottky emission is the dominant mechanism and the Poole–Frenkel emission occurs only in the high voltage region. The energy distribution of interface states is determined from the forward bias I–V characteristics by taking into account the bias dependence of the effective barrier height. It is observed that the density value of interface states for the annealed samples with interfacial layer is lower than that of the density value of interface states of the as-deposited sample.     

Optical absorption spectrum of Ni2+ doped in ammonium zinc sulphate

The optical absorption spectrum of Ni²⁺ ion doped in ammonium zinc sulphate has been studied at room and liquid air temperatures. From the nature and the positions of the bands a successful interpretation of all the bands could be made assumingO _h symmetry for the Ni²⁺ ion in the crystal. The fine splitting of the³ T ₁ ¹ band at liquid air temperature has been successfully interpreted to be due to spin-orbit interaction. The crystal field and spin-orbit parameters derived areDq=1000 cm⁻¹;B=750 cm⁻¹;C=3.45B andξ=600 cm⁻¹.     

Synthesis of a Tricyclic Steroid Intermediate Via an Oxy-Cope Rearrangement

A tricyclic intermediate with the potentials to be elaborated to a A-ring aromatic or non-aromatic steroid system, bearing a methyl at C₈ carbon, has been synthesized via an oxy-Cope rearrangement from the readily available α-tetralone.     

Spectroscopic studies of transition metal ions in spessartine garnet

From optical absorption studies at room and liquid air temperatures and from Mössbauer spectrum, the absorption bands of spessartine garnet are attributed to Mn²⁺ and Fe²⁺ ions. The energy matrices ofd ⁵ andd ⁶ configurations are solved and the experimental data of Mn²⁺ and Fe²⁺ bands are fitted with the calculated values to solve for the Racah and crystal field parameters.     

Electronic absorption in silicate mineral of copper

The electronic absorption spectrum of chrysocolla, a silicate mineral of copper, has been studied at room and liquid air temperatures. The observed bands were satisfactorily explained as belonging to Cu²⁺ ion subjected to tetragonal and spin-orbit fields. A good fit between the theoretical and observed band positions was obtained for the following crystal field parameters:Dq=–1400 cm^–1 Ds=–3000 cm^–1 Dt=–800 cm^–1 =–800 cm^–1     

Synthesis of Spirodiones and Their Structure Determination by X-Ray Crystallography

A rational synthesis of Spiro bicyclo (5,4) dec-2-ene-3-methyl-1,6-dione (1) and Spiro bicyclo (5,5) undec-2-ene-3-methyl-1,7-dione (2) from 2-acetyl cycloalkanone is described. Compounds (1) and (2) have very high potentials as important precursors to many naturally occurring bridged tricyclic compounds. A single crystal X-ray crystallographic study of compound (2) was carried out to establish the structure as chemical and spectral methods proved rather inadequate.