ELECTRON PARAMAGNETIC RESONANCE OF Ti3+ IONS IN TlAl(SO4)2∙12 H2O

1966 ◽  
Vol 44 (10) ◽  
pp. 2329-2335 ◽  
Author(s):  
John A. MacKinnon ◽  
Gerald F. Dionne
Keyword(s):  
Energy Level ◽  
Point Group ◽  
Orbital Energy ◽  
Field Energy ◽  
Ultraviolet Region ◽  
Orthorhombic Symmetry ◽  
Paramagnetic Resonance ◽  
Crystal Electric Field ◽  
X Band ◽  
G Factors

The paramagnetic resonance spectrum of Ti3+ ions in thallium alum (TlAl(SO4)2∙12 H2O) single crystals has been studied in the {100} planes at 4.2 °K with an X-band microwave spectrometer. The spectrum is an analogue of that reported by Dionne for Ti3+ ions in rubidium alum (RbAl(SO4)2∙12 H2O), but differs in that the lines occur at lower values of the magnetic field, and that no superhyperfine splitting was observed. As in the case of Rb alum, the spectrum was explained by considering a model of 12 magnetic complexes, the complexes being related to each other through the symmetry elements of the [Formula: see text] point group of the alum lattice. The three g factors for the spin Hamiltonian with [Formula: see text] were found to be 1.938, 1.834, and 1.790—within an accuracy of ± 0.005. The three different g factors were taken as evidence for a crystal electric field of orthorhombic symmetry. The orbital energy-level splittings required to give the observed g factors were calculated by a degenerate perturbation method. Since the crystals were colorless and since no value for 10 Dq is available in the literature, a unique set of splitting parameters could not be obtained. By giving the spin-orbit coupling constant λ values between 150 and 110 cm−1, a range of crystal-field energy-level splittings was determined, all of which predict that the cubic splitting 10 Dq is in the ultraviolet region of the frequency spectrum.

ELECTRON PARAMAGNETIC RESONANCE EXPERIMENTS WITH Ti3+ IONS IN RbAl(SO4)2 ∙ 12H2O

1964 ◽  
Vol 42 (12) ◽  
pp. 2419-2428 ◽  
Author(s):  
Gerald F. Dionne
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Resonance Spectrum ◽  
Point Group ◽  
Orthorhombic Symmetry ◽  
Spin Hamiltonian ◽  
Paramagnetic Resonance ◽  
Crystal Electric Field ◽  
Microwave Spectrometer ◽  
X Band ◽  
Electron Paramagnetic

The paramagnetic resonance spectrum of the Ti3+ ion in cubic RbAl(SO4)2 ∙ 12H2O single crystals has been studied in the {100} and {110} planes at 4.2 °K with an X-band microwave spectrometer. The spectrum, which consists of a maximum of 12 lines, has been explained by considering a model of 12 magnetic complexes which are related to each other through the symmetry elements of the Th = (2/m)3 point group of the Rb alum lattice. For the spin Hamiltonian with [Formula: see text], three g factors have been determined—1.895, 1.715, and 1.767— within an accuracy of ±0.002, indicating the existence of a crystal electric field of orthorhombic symmetry.

Electron Paramagnetic Resonance of Ti3+ Ions in KAl(SO4)2∙12H2O

1975 ◽  
Vol 53 (8) ◽  
pp. 841-842 ◽  
Author(s):  
John A. MacKinnon ◽  
M. Shannon
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Single Crystals ◽  
Resonance Spectrum ◽  
Point Group ◽  
Spin Hamiltonian ◽  
Potassium Alum ◽  
Paramagnetic Resonance ◽  
Microwave Spectrometer ◽  
X Band ◽  
Electron Paramagnetic

The paramagnetic resonance spectrum of Ti3+ ions in potassium alum (KAl(SO4)2∙12H2O) single crystals has been studied in the {100} planes at 4.2 K with an X band microwave spectrometer. The spectrum is an analogue of that reported by Dionne for Ti3+ ions in rubidium alum (RbAl(SO4)2∙12H2O) and by MacKinnon and Dionne for Ti3+ ions in the thallium alum (TlAl(SO4)2∙12H2O). The spectrum was explained with a model of 12 magnetic complexes, the complexes being related to each other through the symmetry elements of the [Formula: see text] point group of the alum lattice. The three g factors for the spin Hamiltonian with S = 1/2 were found to be 1.979, 1.898, and 1.828, with an accuracy of ±0.005.

The g Factors and Defect Structure of Orthorhombic Dy3+ Ions in CdF2 Crystals

2006 ◽  
Vol 61 (1-2) ◽  
pp. 87-90
Author(s):  
Hui-Ning Dong ◽  
Shao-Yi Wu ◽  
Wei-Dong Chen ◽  
Deng-Feng Li
Keyword(s):  
Alkali Metal ◽  
Crystal Field ◽  
Metal Ion ◽  
Orthorhombic Symmetry ◽  
Spin Orbit Coupling ◽  
Field Interaction ◽  
Paramagnetic Resonance ◽  
Co Doped ◽  
The Ideal ◽  
G Factors

The electronic paramagnetic resonance g factors gx, gy and gz of an orthorhombic Dy3+ center in CdF2 are studied by the perturbation formulae of the g factors for a 4f9 ion in orthorhombic symmetry. In these formulae, the contributions to g factors due to J-mixing among the ground 6H15/2, the first excited 6H13/2 and the second excited 6H11/2 states via crystal-field interaction, lead to admixtures among the states with the same J-value via spin-orbit coupling. In addition, the admixtures between the lowest Kramers doublet Γγ and other 20 Kramers doublets Γ x within the states 6HJ (J = 15/2, 13/2 and 11/2) via crystal-field and orbital angular momentum interactions are considered. In the above orthorhombic center, the impurity Dy3+ is associated with co-doped crystals with alkali metal ions in the [110] axis. By analyzing the g factors, we find that the impurity Dy3+ ion does not reside in the ideal Cd2+ site but moves towards the co-doped alkali metal ion along the [110] direction by a displacement Δ Z ≈ 0.272 Å.

Tetranuclear supramolecular structures containing phthalocyanine cores

2007 ◽  
Vol 11 (07) ◽  
pp. 531-536 ◽  
Author(s):  
Ibrahim Özçesmeci ◽  
Sadik Güner ◽  
Ali Ihsan Okur ◽  
Ahmet Gül
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Energy Levels ◽  
Water Soluble ◽  
Orbital Energy ◽  
Characteristic Line ◽  
Spin Hamiltonian ◽  
Paramagnetic Resonance ◽  
X Band ◽  
Hamiltonian Parameters ◽  
Electron Paramagnetic

A metal-free phthalocyanine with four pyridyl donor groups, bound through ethylthio ester bridges on the periphery, have been prepared. The pyridine donors were quaternized with iodomethane to a water-soluble tetracationic phthalocyanine. The tetranuclear supramolecular phthalocyanine was prepared by the coordination of peripheral pyridine donors with VO(acac)2. The paramagnetic tetranuclear structure was studied in powder and solution forms by the electron paramagnetic resonance (EPR) technique. Electron paramagnetic resonance studies, together with the other spectral data confirmed the presence of identical pyridine-coordinated VO(acac)2 paramagnetic centers attached to the peripheral positions of the phthalocyanine core. The X-band EPR signals recorded from powder and solution forms of supramolecules have a characteristic line shape that proves the presence of axial symmetry around the paramagnetic vanadium ions. The anisotropic Lande splitting factors were calculated as g ∥ < g ⊥ < g e = 2.0023. Orbital energy levels for magnetic electrons were determined from theoretically fitted Spin Hamiltonian parameters.

EPR of Cu2+ in Ferroelectric LiH3(SeO2)2 Single Crystals

1982 ◽  
Vol 37 (9) ◽  
pp. 1092-1093 ◽  
Author(s):  
Mohd. Waseem ◽  
R. Dayal ◽  
Vimal Kumar Jain
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Single Crystals ◽  
Orthorhombic Symmetry ◽  
Spin Hamiltonian ◽  
Paramagnetic Resonance ◽  
X Band ◽  
Electron Paramagnetic ◽  
Bond Direction

Abstract The electron paramagnetic resonance of Cu2+ in ferroelectric LiH3(SeO3)2 has been studied at 298 K in X-band. The Cu2+ appears to substitute Li+ in the lattice with the z-axis nearly along the Li-O(6) bond direction. The spectra have been analysed using the spin-Hamiltonian appropriate for Cu2+ in orthorhombic symmetry.

scholarly journals The Effects of Molecular Packing Behavior of Small-Molecule Acceptors in Ternary Organic Solar Cells

2021 ◽  
Vol 11 (2) ◽  
pp. 755
Author(s):  
Eunhee Lim
Keyword(s):  
Solar Cells ◽  
Energy Level ◽  
Ternary System ◽  
Small Molecule ◽  
Organic Solar Cells ◽  
Orbital Energy ◽  
Working Mechanism ◽  
Energy Level Structure ◽  
The Third ◽  
Molecular Backbone

Herein, two diketopyrrolopyrrole (DPP)-based, small-molecule isomers, o- and p-DPP-PhCN, were introduced as acceptors in ternary organic solar cells (OSCs). The isomers have the same molecular backbone but differ in the positions of the cyanide (CN) substituents (ortho and para), which greatly affects their packing behavior. Ternary solar cells composed of poly(3-hexylthiophene) (P3HT):DPP-PhCN:phenyl-C61-butyric acid methyl ester (PCBM) were fabricated, and the effects of the different packing behaviors of the third component on the device performance and the working mechanism of the ternary cells were investigated. The addition of o-DPP-PhCN with a relatively high-lying lowest unoccupied molecular orbital energy level resulted in an increase in the open-circuit voltage (VOC) in the ternary devices, demonstrating the alloy-like structure of the two acceptors (o-DPP-PhCN and PCBM) in the ternary system. However, the p-DPP-PhCN-based ternary cells exhibited VOC values similar to that of a P3HT:PCBM binary cell, irrespective of the addition of p-DPP-PhCN, indicating a cascade energy-level structure in the ternary system and an effective charge transfer from the P3HT to the PCBM. Importantly, by increasing the addition of p-DPP-PhCN, the short-circuit current density increased substantially, resulting in pronounced shoulder peaks in the external quantum efficiency responses in the long-wavelength region, corresponding to the contribution of the photocurrent generated by the light absorption of p-DPP-PhCN. Despite sharing the same molecular backbone, the two DPP-PhCNs exhibited substantially different packing behaviors according to the position of their CN substituents, which also greatly affected the working mechanism of the ternary devices fabricated using the DPP-PhCNs as the third component.

scholarly journals Photoreactivity of Hair Melanin from Different Skin Phototypes—Contribution of Melanin Subunits to the Pigments Photoreactive Properties

2021 ◽  
Vol 22 (9) ◽  
pp. 4465
Author(s):  
Krystian Mokrzynski ◽  
Shosuke Ito ◽  
Kazumasa Wakamatsu ◽  
Theodore G. Camenish ◽  
Tadeusz Sarna ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Singlet Oxygen ◽  
Near Infrared ◽  
Paramagnetic Resonance ◽  
Time Resolved ◽  
W Band ◽  
Epr Oximetry ◽  
X Band ◽  
Hair Samples ◽  
Electron Paramagnetic

Photoreactivity of melanin has become a major focus of research due to the postulated involvement of the pigment in UVA-induced melanoma. However, most of the hitherto studies were carried out using synthetic melanin models. Thus, photoreactivity of natural melanins is yet to be systematically analyzed. Here, we examined the photoreactive properties of natural melanins isolated from hair samples obtained from donors of different skin phototypes (I, II, III, and V). X-band and W-band electron paramagnetic resonance (EPR) spectroscopy was used to examine the paramagnetic properties of the pigments. Alkaline hydrogen peroxide degradation and hydroiodic acid hydrolysis were used to determine the chemical composition of the melanins. EPR oximetry and spin trapping were used to examine the oxygen photoconsumption and photo-induced formation of superoxide anion, and time-resolved near infrared phosphorescence was employed to determine the singlet oxygen photogeneration by the melanins. The efficiency of superoxide and singlet oxygen photogeneration was related to the chemical composition of the studied melanins. Melanins from blond and chestnut hair (phototypes II and III) exhibited highest photoreactivity of all examined pigments. Moreover, melanins of these phototypes showed highest quantum efficiency of singlet oxygen photogeneration at 332 nm and 365 nm supporting the postulate of the pigment contribution in UVA-induced melanoma.

INVESTIGATIONS OF ELECTRON-PARAMAGNETIC-RESONANCE PARAMETERS OF OCTAHEDRAL (CrO6)9- and (MnO6)8- CLUSTER IN MgTiO3:Cr3+, SrTiO3:Cr3+ AND SrTiO3:Mn4+ CRYSTALS

2011 ◽  
Vol 25 (21) ◽  
pp. 1779-1785
Author(s):  
MINJIE WANG ◽  
LIANXUAN ZHU ◽  
JIANLIANG DANG
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Crystal Field ◽  
Valence State ◽  
Spin Orbit ◽  
Contribution Rate ◽  
Paramagnetic Resonance ◽  
Epr Parameters ◽  
Experimental Values ◽  
Electron Paramagnetic ◽  
G Factors

The complete high-order perturbation formulas are established by both crystal-field (CF) and charge-transfer (CT) mechanisms. The EPR g factors of MgTiO 3: Cr 3+, SrTiO 3: Cr 3+ and SrTiO 3: Mn 4+ crystals are calculated from the formulas. The calculations of the EPR g factors are in agreement with the experimental values. The contribution rate of the CT mechanism (|ΔgT/ΔgF|) to EPR parameters, increases with the growth of the valence state for the 3dn ions in the crystals. For the higher valence state 3d3 ion Mn 4+ in crystals, the explanation of the EPR parameters reasonably involves both CF and CT mechanisms. The g values are also given from one-spin-orbit-parameter model and crystal-field (CF) mechanism for comparison.

An X-band time domain electron paramagnetic resonance spectrometer

Pramana ◽  
1986 ◽  
Vol 27 (5) ◽  
pp. 661-677 ◽  
Author(s):  
Ranjan Das ◽  
Balu Venkataraman ◽  
Vinod R Bhagat ◽  
Ajit S Ghangrekar ◽  
Thomas Kuruvilla ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Time Domain ◽  
Electron Paramagnetic Resonance Spectrometer ◽  
Paramagnetic Resonance ◽  
X Band ◽  
Electron Paramagnetic

X-band electron paramagnetic resonance of a quasi-bidimensional molecular composite [NH3(CH2)4NH3]CuCl4

1996 ◽  
Vol 97 (8) ◽  
pp. 669-674 ◽  
Author(s):  
Jean-Claude Bissey ◽  
René Berger ◽  
Pierre Béziade ◽  
Nguyen-Ba Chanh ◽  
Thierry Maris ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Paramagnetic Resonance ◽  
Band Electron ◽  
X Band ◽  
Electron Paramagnetic
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