Mössbauer Spectroscopic Study Of An Iron(III) Complex With Crown Porphyrin. Pankratov D.A., Stukan R.A., Al'Ansari Ya.-F., Savinkina E.V., Kiselev Yu.M. //Russian Journal of Inorganic Chemistry. 2011. V. 56. № 10. P. 1603-1608
A complex of 57Fe with 5-{4-[((4′-hydroxybenzo-15-crown-5)-5′-yl)diazo]phenyl}-10,15,20-triphenylporphyrin was studied by Mössbauer spectroscopy. The presence of signals of two types in the spectra (a doublet and an extended absorption band over a wide velocity range) suggests that the Fe atoms occupy two structurally different positions in this complex. The dependences of the doublet asymmetry on temperature and the angle between the normal to the sample plane and the γ-ray beam were studied. The isomer shift δ of the doublet in the temperature range from 360 to 5 K changes from 0.25 to 0.41 mm/s, while the quadrupole splitting remains virtually unchanged (Δ ≈ 0.65 mm/s). The relaxation-type absorption over a wide velocity range, the relative area of which strongly varies with temperature, can be described by a broad singlet with the following parameters: δ = 0.30–0.44 mm/s and Γ = 2.8–3.38 mm/s. According to the δ values, both signals are due to Fe(III) derivatives.
The structures and properties of metalloporphyrins (MPs), such as hemoglobin, chlorophyll, and vitamin В12, involved in vital processes depend on the complexing metal and the peripheral substituents. A great number of MPs are chemically inert and thermally stable, have high molar absorption coefficients in the UV-Vis and near-IR ranges, and show reversible redox transitions. This accounts for the interest in comprehensive study of the corresponding properties using a variety of physicochemical techniques.
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16.2.2. Оборудование и реактивы - Соединительный солевой мостик
Солевой мостик выполнен из непрозрачной ПВХ трубки диаметром 15 мм, длина которой зависит от выбранной глубины. Она обеспечивает постоянный контакт с почвой. Окно (рис.) размером в несколько миллиметров вблизи дна трубки обеспечивает электрический контакт с почвой. Оно заклеено куском фильтровальной бумаги. Верхний конец мостика выступает из почвы; он немного больше по размеру для поддержания электрода сравнения в процессе измерений. Этот блок наполняют нагретой (до текучести) смесью 350 г/л KCl + 3% агара и несколькими крупинками фенола для консервации и затем закрывают до затвердения геля. Описанный солевой мостик похож на тот, что был предложен Венеманом и Пикерингом (Veneman и Pickering, 1983).
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Electron paramagnetic resonance spectra near the spin-glass transition in iron oxide nanoparticles. Koksharov Yu.A., Gubin S.P., Kosobudsky I.D., Yurkov G.Yu., Pankratov D.A., Ponomarenko L.A., Mikheev M.G., Beltran M., Khodorkovsky Y., Tishin A.M. //Physical Review B: Condensed Matter and Materials Physics. 2001. V. 63. № 1. P. 124071-124074
Electron paramagnetic resonance (EPR) in iron-oxide nanoparticles (∼ 2.5 nm) embedded in a polyethylene matrix reveals the sharp line broadening and the resonance field shift on sample cooling below TF ≈ 40 K. At the same temperature a distinct anomaly in the field-cooled magnetization is detected. The temperature dependences of EPR parameters below TF are definitely different than those found for various nanoparticles in the superparamagnetic regime. In contrast to canonical bulk spin glasses, a linear fall-off of the EPR linewidth is observed. Such behavior can be explained in terms of the random-field model of exchange anisotropy.
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Emission Mössbauer Study Of "Cobalt Peroxide". Pankratov D.A., Portachenko T.A., Perfil'ev Yu.D. //Moscow University Chemistry Bulletin. 2008. V.49. №5. P.292-296.
The product interaction cooled alcohol solutions of the cobalt (II) chloride with hydrogen peroxide as described as CoO2 studied by emission Möessbauer spectroscopy. We show that dark green product is the cobalt (III) oxide.
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