EPR studies of Cu2+ in tetraaqua-di(nicotinamide) Zn(II)-saccharinate single crystals

Electron paramagnetic resonance (EPR) studies of copper ions, Cu(II), as paramagnetic impurity in tetraaqua-di(nicotinamide) Zn(II)-saccharinates single crystals [Zn(nic)2(H2O)4](sac)2, have been investigated at ambient temperature. The detailed EPR analysis shows the only one site and the copper ion entered the lattice substitutionally in place of Zn(II). The spin-Hamiltonian parameters were obtained from the single crystal EPR analysis. By using the EPR data, molecular bonding coefficient and the Fermi contact interaction terms have been evaluated. Superhyperfine splittings were observed.     

Electron paramagnetic resonance and optical studies of Cu2+ doped bis(thiourea)cadmium chloride single crystal

Electron paramagnetic resonance (EPR) and optical studies have been carried out on Cu²⁺ doped bis(thiourea)cadmium chloride single crystal, which belongs to a potential semi-organic non-linear material, at room temperature. The spin Hamiltonian parameters were determined as g_xx = 2.04331, g_yy = 2.04373, g_zz = 2.05750 and A_xx = 91G, A_yy = 115G, A_zz = 136G. These parameters suggest that the spectroscopic splitting parameter g and hyperfine splitting parameter A exhibit rhombic symmetry. The optical study reveals that the non-linear optical property of the host lattice has been enhanced due to Cu²⁺ doping.     

Growth and characterization of a new metal-organic nonlinear optical bis (thiourea) cadmium zinc chloride single crystals

A new semiorganic nonlinear optical bis (thiourea) cadmium zinc chloride (BTCZC) crystal has been synthesized. BTCZC single crystals were grown from aqueous solution by slow evaporation technique. The solubility of BTCZC has been determined for various temperatures. Single crystal X-ray diffraction (XRD) study has been carried out to identify the lattice parameters. Fourier transform infrared (FTIR) studies confirm the various functional groups present in the grown crystal. The transmission and absorption spectra of this crystal show that the lower cut off wavelength lies at 260nm. The thermal analyses confirmed that the crystal is stable upto 201 degrees C. The nonlinear optical (NLO) property of the grown crystal has been confirmed by Kurtz-powder second harmonic generation (SHG) test.     

Diffusion of Cs+ and Zn2+ through Nafion-117 ion exchange membrane

This paper discusses the diffusion of Cs⁺ and Zn²⁺ ions through Nafion-117 cation exchange membrane using radiotracer technique. The validity of the Donnan's equation is checked for these ions using⁶⁵Zn and¹³⁷Cs radiotracers. The paper also discusses the diffusion of Cl^– and I^– anions studied by using³⁶Cl and¹³¹I radiotracers. The probable mechanism of diffusion of these anions in the presence of Zn²⁺ cations is suggested.     

EPR of VO2+ in double format, Ba2Zn(HCOO)6(H2O)4 single crystals

VO(2+) doped single crystal of Ba(2)Zn(HCOO)(6)(H2O)(4) (BZFA) were investigated using electron paramagnetic resonance (EPR) technique at ambient temperature. Detailed investigation of EPR spectra indicated that the VO(2+) substitutes the Zn(2+) in the structure. The sites with different orientations were observed for VO(2+) in Ba(2)Zn(HCOO)(6)(H2O)(4).single crystal, but the only intense site among these sites was evaluated to obtain spin-Hamiltonian parameters, which are the principal axis values of the g and the hyperfine tensors. The covalent bonding parameter for VO(2+) and Fermi contact term were calculated using the spin-Hamiltonian parameters.     

EPR studies of VO2+ ions in kainite single crystals

Electron paramagnetic resonance (EPR) spectra of VO2+ ions doped in Kainite (a mineral salt) single crystals and powder were recorded at room temperature at X-band frequencies.The angular variation studies of the spectra indicate that the VO2+ ion enters Mg2+ ion site substitutionally. The principal values of g and A-tensors were determined from the EPR spectral studies. Using these EPR parameters, the molecular orbital bonding parameters of VO2+ ion in the lattice have been evaluated and discussed.     

X-Ray storage luminescence of BaFCl:Eu2+ single crystals

Temperature behaviors of X-ray luminescence (XL), photoluminescence (PL), photostimulated luminescence, and thermoluminescence (TL) were studied in BaFCl:Eu2+ single crystals from room temperature to liquid nitrogen temperature. Six emissions at 275, 315, 365, 385, 435, and 500 nm were observed in the XL spectra and are attributed to Cl excitons, V(k)(Cl2-), the 4f65d1 (2e(g)) --> 4f7 (8S(7/2)) transition of Eu2+, and oxygen vacancies, respectively. Three emission peaks at 315, 365, and 390 nm were observed in the PL and TL measurements. These three emissions are from the transitions of 4f7(6I(7/2)) --> 4f7(8S(7/2)), 4f7(6P(7/2)) --> 4f7(8S(7/2)), and 4f65d1 (2e(g)) --> 4f7(8S(7/2)) of Eu2+, respectively. In our measurements, we observed that the emission of Eu2+ increases in intensity upon beta-irradiation and did not see any signals related to Eu3+ ions, which indicates that Eu2+ ions might not be oxidized to Eu3+ upon X-ray or beta-irradiation. Instead, the color centers, Cl excitons, and oxygen defects are created and are stable at room temperature, and they might play a key role in the storage luminescence.     

Laser Raman study of single crystals of deuterated cadmium fluorosilicate

A laser Raman study of oriented single crystals of CdSiF₆:6D₂O at room temperature as well as at 10 K in all the six polarization geometries has been made. Also a detailed temperature dependent Raman study from room temperature to 10 K in (yy) polarization in the region of internal vibrations and lattice modes has been made. Abrupt changes have been observed in frequency shift, line-width and intensity of some of the bands at about 235 K. Some doubly degenerate modes show splitting at the same temperature. From these observations a phase change at about 235 K is inferred for this salt. It has been suggested that when the system is cooled, the lattice contracts and the water molecules lose their reorientational freedom to some extent which might result in the distortion of the [Cd(OD₂)₆]²⁺ octahedra triggering a phase transition.     

红薯提取液荧光猝灭的Zn2+检测

人体大量摄入锌时易引起中毒,对锌污染的监测十分重要[1,2].锌离子的检测方法主要有电化学分析法[3-5]、光化学分析法[6,7]、原子吸收分光光度法[8]等.     

光度检测-低压离子色谱法同时分析水溶液中铜、锌

用吡啶-(2-偶氮-4-)雷琐辛(PAR)作柱后衍生剂,在优化的衍生和色谱条件下,使用可见光检测一低压离子色谱法同时测定了水溶液中铜和锌。在低压阳离子色谱柱上,用酒石酸．柠檬酸作流动相,在520nm处检测,得到线性良好的工作曲线,铜和锌的检出限均为0．05μg／mL。利用该法分析了环境水样中的铜和锌,其标准加入回收率分别为99％～102％,97％～104％。     

Crystal structure and EPR studies of doped Cu2+ ion in [Zn(sac)2(en)2] single crystal

The tran-bis(ethylenediamine)bis(saccharinato)Zinc(II), [Zn(sac)₂(en)₂] (ZSED), (en: ethylenediamine and sac: saccharinate) complex has been synthesized and its crystal structure has been determined by X-ray diffraction analysis. The compound crystallizes in space group P2₁/c. The Zn(II) ion is hexa-coordinated by four nitrogens of two bidentate en ligands composing the basal plane and two nitrogen atoms from the monodentate two sac ligands (N-bonded) occuping the axial sites, adopting an elongated octahedral sphere. Both en and sac ligands occupy the trans positions of the coordination octahedron. The Zn(II) ion in title compound sits on a inversion centre and is octahedrally coordinated two bidentate en (ethylenediamine) and two sac (saccharinate) (N-bonded) ligands. The magnetic environments of Cu²⁺ doped [Zn(sac)₂(en)₂] complex have been identified by electron paramagnetic resonance (EPR) technique. Cu²⁺ doped ZSED single crystals have been studied at room temperature in three mutually perpendicular planes. The calculated results of the Cu²⁺ doped ZSED indicate that Cu²⁺ ion contains two magnetically inequivalent Cu²⁺ sites in distinct orientations occupying substitutional positions in the host lattice and show very high angular dependence.     

Electron paramagnetic resonance studies of Cu2+ ion in tetraaqua-di(nicotinamide)Ni(II)-saccharinates single crystals

X-band (approximately 9.8 GHz) electron paramagnetic resonance (EPR) measurement at ambient temperature in three mutually perpendicular planes have been carried out on a single crystal of Cu2+ doped mixed ligand complex of Ni(II) with saccharin and nicotinamide [Ni(Nic)2(H2O)4](sac)2. The angular dependent spectra showed that the Cu2+ ion enters Ni2+ sites in the lattice and distorted local environment of Ni2+ site. The principal g and A values, covalency parameter (alpha'2), mixing coefficients (alpha and beta) and Fermi contact term (K) have been evaluated from the EPR analysis. The ground-state wave function of the Cu2+ ion has been constructed using the alpha'2, alpha and beta values. The nature of the distortion present in the lattice is obtained from the values of the mixing coefficients.     

Ratiometric Zn2+ sensor and strategy for Hg2+ selective recognition by central metal ion replacement

Strategies of both self-assembly and metal ion replacement were adopted in the development of new metal ion sensors for Zn2+ and Hg2+. Ligand BPBA, phenylene-bridged bis(pyrrol-2-ylmethyleneamine), could self-assemble to form a molecular square in the presence of Zn2+, which showed strong emission in solution. The fluorescent emission of formed BPBA-Zn2+ dropped with the addition of Hg2+. BPBA could be a good Zn2+ sensor candidate and BPBA-Zn2+ could be a good Hg2+ sensor candidate based on the mechanisms of the chelation-enhanced fluorescence effect and the replacement of central metal ion induced chelation-enhanced fluorescence quenching effect, respectively.     

Free ion and crystal field splitting of Tm3+ in single crystals of thulium sulfate octahydrate

We report a detailed analysis of the free ion centers of gravity and the crystalline electric field (CEF) splitting of the 4£¹²[SL]-J levels of Tm³⁺ in single crystals of Tm₂(SO₄)₃·8H₂O. A new interpretation of the ³P₀ and ¹l₆ centers of gravity in the sulfate lattice is given. A free ion calculation has been completed and the resulting intermediately coupled wavefunctions have been used to calculate the CEF splitting. Forty-three observed crystalline Stark level differences were used in the CEF analysis and could be accounted for to better than 5%. The CEF parameters are found to be very similar to those previously reported for Ho³⁺ in single crystals of Ho₂(SO₄)₃·8H₂O. The CEF splitting calculation predicts the presence of a pair of nearly twofold degenerate ground levels and the respective spectroscopic splitting factors in agreement with experiment.     

ESR and optical study of Mn2+ doped ammonium selenate single crystals

ESR and optical absorption studies of manganese doped ammonium selenate single crystals are performed at X-band and room temperature to ascertain the site symmetry and location of impurity ions in the lattice. Manganese ions are expected to enter the lattice interstitially. Various spin Hamiltonian parameters are determined. Optical absorption study is also done and associated distortion in the crystal lattice is estimated.     

Solid-state ion selective electrode based on polypyrrole conducting polymer nanofilm as a new potentiometric sensor for Zn2+ ion

A pencil graphite electrode (PGE) electrodeposited by a polypyrrole conducting polymer doped with tartrazine (termed as PGE/PPy/Tar) was prepared and used as a zinc (II) solid-state ion-selective electrode. For the preparation of the zinc sensor electrode, electrodeposition of a polypyrrole nanofilm was carried out potentiostatically (E _app?=?0.75 V vs SCE) in a solution containing 0.010 M pyrrole and 0.001 M tartrazine trisodium salt. A pencil graphite and Pt wire were used as working and auxiliary electrodes, respectively. The introduced electrode in the current paper can be fabricated simply and was found to possess high selectivity, exhibited wide working concentration range, sufficiently rapid response, potential stability, and very good sensitivity to Zn (II) ion. The sensor electrode showed a linear Nernstian response over the range of 1.0?×?10^?5 to 1.0?×?10^?1 M with a slope of 28.23 mV per decade change in zinc ion concentration. A detection limit of 8.0?×?10^?6 M was obtained. The optimum pH working of the electrode was found to be 5.0.     

EPR and optical study of Mn2+ doped ammonium tartrate single crystals

EPR study of Mn2+ doped ammonium tartrate single crystals is carried out at room temperature. The spin Hamiltonian parameters are: gx=1.9225+/-0.0002, gy=1.9554+/-0.0002, gz=2.1258+/-0.0002, A=(78+/-2) x 10(-4) cm(-1), B=(75+/-2) x 10(-4) cm(-1), D=(191+/-2) x 10(-4) cm(-1), E=(61+/-2) x 10(-4) cm(-1) and a=(22+/-1) x 10(-4) cm(-1) for site I and gx=1.9235+/-0.0002, gy=1.9574+/-0.0002, gz=2.0664+/-0.0002, A=(78+/-2) x 10(-4) cm(-1), B=(75+/-2) x 10(-4) cm(-1), D=(180+/-2) x 10(-4) cm(-1), E=(57+/-2) x 10(-4) cm(-1) and a=(22+/-1) x 10(-4) cm(-1) for site II, respectively. The observed optical bands are fitted with inter-electronic repulsion parameters (B and C), crystal field parameter (Dq) and Trees correction (alpha) and the values found are B=752, C=2438, Dq=765 and alpha=76 cm(-1). The data obtained are further used to discuss the surrounding crystal field and the nature of metal-ligand bonding in the crystal.