The Faraday effects of 14 lanthanide(III) ion solutions were systematically analyzed on the basis of the Faraday C term. The effective transition probability, K, which measures the magneto-optical contribution of the 4f(n) --> 4f(n-1)5d transition to the molar Verdet constant, was determined. Linear correlations between K and the square root of the molar magnetic susceptibility of the lanthanide(III) ions, chi(m)(1/2), were obtained. From the observed new regularity, K for promethium(III) was estimated.
The Faraday effect, discovered in 1846 by M. Faraday, 1,2 is a typical magneto-optical phenomenon in which linearly polarized light through a material is rotated, when a magnetic field is applied parallel to the light beam. The rotation angle, qF, depends on the optical path length, l, and the magnetic flux density, B, as well as the magneto-optical property of the material, which is characterized by the Verdet constant, V, as presented by the equation:The physical meaning of the Verdet constant is magneto-complex birefringence, and it is shown by the following equation, when the material has no absorbance at the observing wavelength:where w is the angular frequency, c the velocity of light and nl and nr the refractive indexes for the left-circularly polarized light and the right-circularly polarized light. The Verdet constant of a diamagnetic material is theoretically thought to reflect the magnetic moments of the ground state and the excited state to the direction of the magnetic field (defined as z-axis) and the electric transition probability in the xy plane at the wavelength of the polarized light. 4,5 The Faraday rotation has been studied mainly for paramagnetic solids and solid films, since it has been extensively used in commercially important magneto-optical memory products. 6-9 As for diamagnetic soft materials, such as organic liquids and polymers, measurement of the Faraday effect is very limited. 10 However, the Faraday effect is thought to have unique information available in analytical chemistry, in that the magnetization can be monitored by light, since all compounds have their own magnetic moments or magnetic susceptibilities, which could be used for identification and speciation. In the case of diamagnetic compounds, the magnetic susceptibility can be estimated by composing the Pascal constants assigned to each atom or bond in the molecular structures. [11][12][13] We have intended to develop a new analytical imaging method to discriminate soft materials by using the Faraday rotation with a pulsed magnetic field. A pulsed magnetic field as high as 10 T can be easily obtained by a small coil, discharging an electric current in a short time from a condenser bank.14 In the present report, some preliminary results that demonstrate the possibility of the Faraday imaging of diamagnetic liquids are described. Figure 1 shows a schematic drawing of the pulsed magnetic field Faraday imaging apparatus used in the present study. A power supply (MAG-2520L-3A, Magnetic Force, Osaka, Japan) has a 2000 mF condenser, which can be operated under 50 -1500 V and a current of less than 3.12 kA. The frame of the coil was made by a fiberglass reinforced plastics (FPR) plate. The size of the coil was 8.5 mm in the bore diameter, and had 27.87 mH/1 kHz in inductance, wound 64 times by 0.5 ¥ 0.75 mm rectangular copper wire (Mitsubishi, Mexcel, EDFB-X). Another coil, a split Helmholtz type coil, was made and used for applying a magnetic field vertically to a capillary cell that contained both water and toluene. The magne...
Experimental Reagents and chemicalsAll of the chemicals were of analytical grade, and were used without further purification. Mo(VI) and P(V) stock solutions were prepared from Na2MoO4·2H2O and NaH2PO4·2H2O, The isomerization reaction of the β-form of 12-molybdophosphate ([PMo12O40] 3-: PMo12) into the α-form in aqueous-organic mixed media containing various salts was extensively investigated with cyclic voltammetry. It was found that the concentration and type of organic solvent and salt strongly affected the rate of the isomerization reaction. When organic solvents with lower permittivity than water were used as auxiliary solvents, and high concentrations of salts were added to the reaction mixture, the β-form of PMo12 (β-PMo12) became more stable, leading to slow isomerization into the α-form (α-PMo12). Based on the results of this study, it is proposed that the isomerization reaction of β-PMo12 into α-PMo12 is caused by the attack of a proton on a corner-shared oxygen atom. Also, the variation of its reaction rate upon the addition of organic solvents and salts is due to interactions between both the protons and the solvents or anions, and between the cations and the PMo12 anion.
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