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The formation of water-soluble metalloporphyrin heterodimers from Fe(III), Cu(II) and Ni(II) complexes of 5,10,15,20-tetrakis(4-carboxyphenyl) porphyrin and 5,10,15,20-tetrakis(4-N-methylpyridyl)porphyrin has been investigated using UV-vis, IR and electron paramagnetic resonance spectra. Absorption and IR spectra confirmed the formation of dimers and electron paramagnetic resonance spectra showed evidence for the metal-metal interactions in the dimers.

The in vitro photodynamic effect of bis(tri-n-hexylsiloxy)silicon phthalocyanine has been evaluated against the melanotic M6 cell line. The results showed that at 10^-5 M dose, LD₅₀ is obtained for a 150 J cm^-2 light dose and LD₉₀ for 540 J cm^-2. Electron spin resonance spectroscopy was used with spin traps to study the type I and type II photochemical pathways involved and to detect active oxygen intermediates such as singlet oxygen, oxygen superoxide and hydroxyl radical. The two mechanisms occurred simultaneously and no change was observed when the phthalocyanine was entrapped in liposomes.

Neutral double-decker radical lutetium(III) diphthalocyanine with eight crown ether substituents bound through oxymethyl bridges has been synthesized from 1-[(benzo-15-crown-5)-4′-yl]oxymethyl-3,4-dicyanobenzene and lutetium(III) acetate. The ESR spectrum confirmed the radical nature of the complex.

PZT(Zr:Ti=52:48) ceramics can be modified by Gd³⁺, giving compositions Pb_1-xGd_x- (Zr_0.52Ti_0.48)1-x/4 O₃ with x = 0.00, 0.01, 0.5, 1, 2, 6 and 10 mole percent. X-ray diffraction patterns show that all PGZT samples are of tetragonal structure and the highest doping should be no more than 2 mole percent Gd at which impurity unreacted oxides start to appear. ESR spectra of PGZT's indicate that Gd³⁺ can enter both A and B sites of the perovskite structure instead of only A site as widely believed. As a result, the tetragonality (c/a ratio) first increases and reaches a maximum at x ≅ 0.8 mole percent and drops as Gd³⁺ enters more A sites. The doping should, however be limited to one mole percent as overdoping proves detrimental to the dielectric and piezoelectric properties of PGZT. The dielectric constant (1 kHz) of the poled samples reaches a maximum value of 1150 at x = 0.02 while the largest d₃₃ value of 160 pC/N is achieved at only lightly doped 0.01 mole percent. Furthermore, the Gd doping has a drastic effect on Q_m and the dissipation factor DF — the former drops sharply while the latter increases with x.

The temperature dependence of the NMR spin-lattice relaxation time is analyzed for preliminary evaluation of the correlation time of the local dynamics of the polymeric chain, for the molten polyisoprene and some polyisoprene-CCl₄ solutions. Complementary information concerning this dynamics were obtained from the analyze of the ESR spectra recorded from the nitroxide molecules (2, 2, 6, 6, tetramethyl piperidin-1-yloxyl) dissolved in the polyisoprene-CCl₄ solutions.

We have studied paramagnetic Mn²⁺ ions present in the shells of today's univalve freshwater snails, Sinotaia ingallsiana (FS), Pila ampullaceal (PA), Pomacea canaliculata lamarck (PCL) and the fossilized freshwater snail (FFS), Viviparus which are abundant in Thailand. The FS, PA and AG shells in our study were ground into fine powder. A set of seven samples was each then separately annealed for 2 hours in air atmosphere at 300°C, 400°C, 450°C, 500°C, 550°C, 600°C and 900°C, respectively, while the FFS powder was characterized as received. The FS, PA and PCL shells mainly consist of aragonite and a fraction of calcite. The heat treatments higher than 450°C of the FS, PA and PCL powder samples resulted in an irreversible phase transformation from aragonite to calcite. However, it is found that the FFS shell is mainly made of calcite, with a minor fraction of aragonite. The crystal structure of high temperature annealed FS, PA and PCL samples are quite similar to that of FFS, which indicates that the metamorphosis (aragonite → calcite) in the FFS shell had occurred but not yet completed, although they remained under the pressure and temperature of the Earth's crust over millions of years. Our detailed ESR spectral analyses of FS, PA, PCL and FFS show that Mn²⁺ ions enter Ca²⁺ sites during a biomineralization process. Typical simulated ESR parameters of FS-500 of Mn²⁺ at a uniaxial site of calcite are g_x=g_y=2.078±0.001, g_z=2.002±0.001, A_x=A_y=87.50±1.00 G, A_z=89.00±1.00 G and D=115±1 G, respectively. It is surprising to find that the ratio of Mn²⁺ concentration present in FFS to those in FS, PA and PCL shells evaluated from ESR spectra is as much as 10:1. It is thus possible to gain some insight of manganese incorporation into the freshwater shells during the biomineralization process.

We report effects of heat treatments on physical properties and finding optimal heating condition to add value to Thai blue sapphires. The color of sapphire arises from the presence of trace 3d-transition ions in its crystal lattice. For blue sapphire, the color is due to a charge transfer mechanism between Fe²⁺ and Ti⁴⁺ ions. However, iron may adopt both Fe³⁺ and Fe²⁺ due to oxygen vacancies. Fe³⁺ and Fe²⁺ yield sapphire yellow and green colors, respectively. Therefore, we have to convert as many as possible of Fe³⁺ to Fe²⁺ by heating the blue sapphire in N₂ atmosphere for 12 h. Experimental results reveal that the ratio of lattice parameter c/a increases with the heating temperature and reaches maximum at 1700°C, which can be caused by displacement of Fe³⁺ ions or more Fe³⁺ ions being converted to Fe²⁺. ESR signals show that the number of Fe³⁺ ions decreases roughly linearly with the heating temperature. The intense sky blue color was achieved after the 1500°C heat treatment, having the ratio ~0.78. The optimal heat treatment should therefore be at 1500°C in flowing N₂ atmosphere for Thai blue sapphires which yield intense sky blue color and good crystal clarity. The blue sapphires exhibited good clarity but light sky blue due to the increase in lightness after the treatment at 1700°C. A monoclinic distortion of the corundum structure has been found to start at the 1600°C treatment by ESR spectrometer. This is also clearly evident from low angle shifts of XRD peaks after heating at 1700°C. We can therefore conclude that the color change of Thai blue sapphires arises from the conversion of Fe³⁺ to Fe²⁺ and thus the change in crystal field. The monoclinic distortion of the crystal structure may also play an important role in coloring the sapphires after the heat treatment at 1600–1700°C.

Electron spin resonance spectroscopy (ESR) was used to study the Mn²⁺ ions in snails of P. canaliculata lamarck (PCL). All these shells are abundant in Thailand. Fractions of aragonite and calcite phase in the shells have been approximately determined by ESR. The PCL shell was ground into fine powders and then four samples were separately annealed for 2 h in air at 400°C, 450°C, 500°C and 600°C, respectively. The phase transition from aragonite to calcite was monitored by X-ray diffractometer (XRD) and electron spin resonance spectrometer (ESR). Our results show that unheated PCL sample is mainly made of aragonite with only a small fraction of calcite. Annealing of the PCL powder sample at the temperature more than 450°C has resulted in the irreversible phase transformation from aragonite to calcite. The analysis of their ESR spectra has shown that Mn²⁺ ions partially substituted Ca²⁺ in the lattices. Finally, the spin Hamiltonian parameters for Mn²⁺ distributed in both aragonite and calcite were evaluated. Our detailed ESR spectral analyses of PCL show that Mn²⁺ ions enter Ca²⁺ sites during a biomineralization process. Typical simulated ESR parameters of PCL-500 of Mn²⁺ at a uniaxial site of calcite are g_x=g_y=2.078(1), g_z=1.999(1), A_x=A_y=87.0 G, A_z=89.00 G and D=115 G, respectively. It is thus possible to gain some insight of manganese incorporation into the fresh water shells during the biomineralization process.

The main purpose of this work is to present the ESR spectra and calculate the spin Hamiltonian parameters of ¹⁴N and ¹⁵N impurities in natural diamond. The ESR spectra of diamond crystal were measured on ESR spectrometer operating at X-band microwave frequency. The results of ESR spectra show that the diamond has a P1 center. This center gives rise to three strong resonance absorption peaks at θ = 90°, φ = 0° due to hyperfine interaction between electron spin and nuclear spin of ¹⁴N. The ESR spectra of ¹⁵N impurity consist of two satellites at the same rotation angle (φ). The effects of isolated substitution nitrogen on carbon atom produced a symmetric distortion from T_d to C_3V symmetry. According to this symmetry, the resonance magnetic field positions of ESR spectra for the rotation angles of 0°, 90° and 180° are almost overlap. The g-factor values and spin Hamiltonian parameters of ¹⁴N and ¹⁵N are: g = 2.0019, A_⊥ = 29.73, A_‖ = 40.24 and g = 2.0019, A_⊥ = −39.90, A_‖ = −57.05, respectively.

A suitable heating condition designed for a particular type of ruby is used to enhance the quality to increase its value. Heating Vietnamese rubies in an oxygen atmosphere may improve color and clarity, and thus increase their prices. The color of rubies is due to the presence of trace amounts of Cr³⁺. Fe³⁺ yields a pale yellow color and the charge transfer mechanism between Fe²⁺ and Ti⁴⁺ gives ruby an undesirable bluish color. Reducing this mechanism is possible by heating the ruby in oxygen so that most of the Fe²⁺ is converted into Fe³⁺ ions and thus they appear a more intense red. By using XRD we found that the c/a ratio of the hexagonal structure was smallest after heat treatment at 1300°C. The number of Fe²⁺ ions converted to Fe³⁺ was detected by an electron spin resonance spectrometer and found to increase with temperature. The ruby appeared a most intense red after heating at 1500°C for 12 hours. The color change is due to both the decrease in c/a ratio and the increase in the number of Fe³⁺ ions. ESR experiments on ruby crystals by rotation about their c-axis show that Fe³⁺ ions are a little off axis before heat treatment. After heat treatment at 1300°C they move to new asymmetric equilibrium positions towards larger O^2- triangles. It is not clear, however, if this Fe³⁺ movement is related to the change in color. The asymmetry may arise due to some O^2- vacancies.

In this report, Fe³⁺ impurity ions present in green sapphire (Al₂O₃) were studied experimentally, by heating a light green sapphire in flowing oxygen atmosphere for 12 h from 1200, 1300, 1400, 1500 and 1600°C, respectively. Electron spin resonance (ESR) spectra in X-band (~9.45 GHz) were recorded by mounting the crystal with the c-axis perpendicular (θ = 90°) to the magnetic field direction. The spectra were recorded and simulated by a numerical diagonalization of spin Hamiltonian matrix in the range from 0 to 180 degrees for every 15 degrees of rotation angle (φ). In our case, only the last two sets of peaks strongly depend on the rotation angle (φ), and each exhibits C₃ symmetry due to two magnetically inequivalent Fe³⁺ sites in the corundum structure. For polycrystalline ESR spectra, seven main Fe³⁺ ESR absorption peaks occur at the resonance magnetic fields of 100.20, 310.24, 486.80, 525.00, 550.60, 761.00 and 777.00 mT respectively. Specifically, ESR signals show that the number of paramagnetic Fe³⁺ ions increase roughly linearly with the heat treating temperature, having the ratio ~1.41 at 1600°C.

Cu-doped Cadmium sulfide (CdS) films were prepared by chemical bath deposition method. Various quantities of Cu were used for mixing. Surface characterization, structure, morphology and defect structures of the films were studied. The structure of all Cu-doped CdS films was a unique CdS cubic phase. The grain size of CdS was decreased when doped with Cu. The F-type defect in the undoped CdS is clearly confirmed by an ESR signal arising from the hyperfine interaction of electron spin (S=1/2) trapped in sulfur vacancies and neighboring cadmium nuclear spin (I=1/2). In the Cu-doped CdS films, the ESR peaks shift towards low fields as the copper concentration is increased. This is due to the change in crystal field experience by Cu²⁺ (3d⁹) ions while the Cd²⁺ signal disappears. The Cu²⁺ ions in the Cd_1-xCu_xS itself are ESR silent due to a very short relaxation time. The dark resistance increased with increasing amount of Cu concentrations up to about 0.03 M. This 0.03 M Cu-doped CdS sample also possesses the maximum photosensitivity.

The CdS : Ni films were fabricated on glass substrates by chemical bath deposition method (CBD), where Ni concentrations are 0%, 10%, 20%, 30% and 40%. X-ray diffractometry (XRD), Raman spectroscopy and electron spin resonance (ESR) were employed to study the film structures. The XRD patterns revealed the presence of cubic CdS and trace of NiS. The Raman spectra were observed at 300 and 600 cm^-1, corresponding to the first and second orders of the longitudinal optical phonon modes. Both results confirm that slightly lower order of crystallinity of CdS : Ni was found at the higher concentration of Ni. The ESR spectra showed the presence of F-type defects in CdS : Ni films. The band gaps of the samples were found to increase with the increase of Ni concentration.

We have studied paramagnetic Mn²⁺ ions present in the freshwater snail, Sinotaia ingallsiana (FS), Viviparus which are abundant in Thailand. The FS shells in our study were ground into fine powder. A set of seven samples was each then separately annealed for 2 hours in air atmosphere at 300°C, 400°C, 500°C, 600°C, 700°C, 800°C and 900°C, respectively. Our detailed ESR spectral analyses of FS show that Mn²⁺ ions enter Ca²⁺ sites during a biomineralization process. The hyperfine coupling constant (A) and zero-field splitting (D) in the ESR spectrum of Mn²⁺ in calcite and aragonite were determined. The spreading of the non-central allowed transitions was analyzed and the experimental transitions were attributed. For calculating the hyperfine coupling constant, five methods for calculating the zero-field splitting, based on the analysis of the allowed and forbidden transitions, were provided. The values of the hyperfine coupling constant range from 87.50 to 89.00 G and those of the zero-field splitting range from 110.00 to 116.00 G.

Temperature dependences of the ESR spectrum in Y₂Cu₂O₅ compound are studied for both polycrystalline and single crystal samples. The g-factors along the main axes are found to be g_a=2.099, g_b=2.048, and g_c=2.21 at room temperature, T=293 K. As temperature decreases, the linewidth ΔH increases in agreement with the Huber’s formula ΔH=A(T_N/(T−T_N))^β+B(θ/T+1) with the following parameters: A=1513±10 Oe, B=509±10 Oe, T_N=7±1 K, θ=18±2 K, β=1.3±0.3. In the vicinity of the Neel Temperature, T_N, the ESR spectrum has a very complicated form indicating the existence of clusters with different internal magnetic fields. Below T_N, a single line symmetrical ESR spectrum is recovered.

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This paper analyzes the effect of 100keV silicon negative ion implantation in semi-insulating gallium arsenide sample for the fluences varying between $1\times 10^{15}$ and $2\times 10^{17}$ioncm${}^{-2}$ using Raman spectroscopy, Rutherford backscattering spectroscopy and Electron spin resonance spectroscopy. The gallium arsenide sample implanted with silicon negative ion for different fluences showed shift in the TO peak position with respect to unimplanted gallium arsenide sample. Increase in the broadening of TO peak was observed in the as-implanted samples, indicating development of stress and phonon confinement due to the incorporation of silicon in gallium arsenide crystal lattice. Annealing of as-implanted samples showed stress relaxation. Increase in RBS backscattering yield was observed in the as-implanted samples. Annealing of as-implanted (with high fluence) sample showed flat RBS yield response. ESR measurement study revealed restructuring of defects in the gallium arsenide sample implanted with fluence of $1\times 10^{17}$ioncm${}^{-2}$ after annealing to the temperature of $300^{\circ }$C.

In this paper, AC and DC electrical properties of organic solar cells based on P3HT:PCBM active layer have been investigated. The performance of such solar cell has demonstrated the efficiency of 2.31% corresponding with short-circuit current density of 6.08 mA ⋅ cm${}^{-2}$, open circuit voltage of 0.64 V and fill factor of 60%. The equivalent circuit and the properties of the supposed interfaces between the layers in the P3HT:PCBM-based solar cell have been estimated. AC properties have demonstrated series capacitance increasing with increasing frequencies, which means series capacitance saves charges and parallel capacitance has decreased with increasing of frequency work as discharge part of charges stored in series capacitance. Also, equivalent series and parallel resistances have demonstrated a decrease from 7 $\mathrm{\Omega }$ and 120 k$\mathrm{\Omega }$ at low frequency to 1 $\mathrm{\Omega }$ and 43 k$\mathrm{\Omega }$ at high frequencies, respectively.

The need for increased memory space and higher speed in computers has fueled the demand for smaller and faster computers. However, as the computer chips miniaturize, it becomes inevitable that we need to look at the possibility of manipulating and addressing atoms and molecules individually. One such possibility is a feasibility study of a quantum computer. In this report, we summarize some of the progress made in experimental realization of quantum computer in the last few years.

The double-decker lutetium(III) phthalocyanine [(C₆H₁₃S)₈Pc]₂Lu was investigated by electrochemical and spectroelectrochemical methods and comparisons made to previously investigated [(C₁₂H₂₅S)₄Pc]₂Lu and (Pc)₂Lu under the some experimental conditions. All three compounds undergo a single reversible one-electron oxidation and up to four reversible one-electron reductions in CH₂Cl₂ containing 0.1 M tetra-n-butylammonium perchlorate (TBAP). The octa- and tetra substituted phthalocyanine derivatives exhibit one oxidation and three or four reductions in solution while five reductions can be detected for the two compounds in a gel-like cast film membrane of tetraoctylphosphonium bromide (4C₈P⁺Br⁻) at a basal plane pyrolytic graphite electrode which was immersed in aqueous 0.5 M KCl. The half-wave potentials of these SR substituted complexes in CH₂Cl₂ are negatively shifted by 210-490 mV from E_1/2 values for the same compounds in the aqueous 4C₈P⁺Br⁻ matrix and five reductions of these compounds are observed under the latter experimental conditions. The UV-visible spectra of the compounds were measured in five different oxidation states and ESR spectra were also characterized for the neutral and doubly reduced complexes. As was expected, [(Pc)₂Lu]⁻,{[(C₆H₁₃S)₈Pc]₂Lu}⁻ and {[(C₁₂H₂₅S)₄Pc]₂Lu}⁻ are ESR silent while electrogenerated [(Pc)₂Lu]²⁻, {[(C₆H₁₃S)₈Pc]₂Lu}²⁻ and {[(C₁₂H₂₅S)₄Pc]₂Lu}²⁻ show broad strong signals at g = 2.0046, 2.0041 and 2.0034 with linewidths of 13.9, 16.1 and 12.9, respectively. These signals are indicative of organic free radicals where the unpaired electrons of the dianion are delocalized over two macrocycles.