scholarly journals Dynamics of hindered CF3-rotor in 2,5-bis (trifl uoromethyl )-nitroben zene radical -anion in anhydro us DMF. A temperature - activation theory of reversible HFS transformations of EPR spectrum

2016 ◽  
Vol 11 (3) ◽  
pp. 31-38
Author(s):  
E. A. Polenov ◽  
P. V. Melnikov
Keyword(s):  
Radical Anion ◽  
Spectral Lines ◽  
Ortho Position ◽  
Temperature Dependent ◽  
Epr Spectrum ◽  
Hindered Rotation ◽  
Activation Theory ◽  
Temperature Activation ◽  
Range Splitting ◽  
Reconstruction Model

The temperature dependence of EPR spectrum of 2,5-bis(trifluoromethyl)nitrobenzene radical anion in anhydrous DMF was investigated. Internal dynamics of hindered rotation of the CF3-group in ortho-position to NO2-group causes HFS modulation. The spectrum changes are reversible and temperature-dependent. An original temperature-activation representation of complex spectral density was proposed instead of the traditional spectral-kinetics representation to explain the observed transformation. The change resulted in a new convenient phenomenological reconstruction model, which allowed simulating the spectra in the whole temperature range. Splitting constants and contributions to the spectral widths of the spectral lines were found. The activation energy of the CF3-group hindered rotation is significant and amounts to 37 kJ/mol.

Erratum: EPR Spectrum of an Azulene Free‐Radical Anion

1962 ◽  
Vol 37 (7) ◽  
pp. 1571-1571 ◽  
Author(s):  
Harmon W. Brown ◽  
Robert C. Jones
Keyword(s):  
Free Radical ◽  
Radical Anion ◽  
Epr Spectrum ◽  
Free Radical Anion

Elektronentransfer und Ionenpaare, 15 [ 1– 3] Radikalanion und Radikal-Kontakt-Ionenpaare von Dimesityl-tetraketon / Electron Transfer and Ion Pairing, 15 [1-3] Radical Anion and Radical Ion Pairs of Dimesityl Tetraketone

1990 ◽  
Vol 45 (8) ◽  
pp. 1197-1204 ◽  
Author(s):  
H. Bock ◽  
P. Hänel ◽  
H.-F. Herrmann
Keyword(s):  
Electron Transfer ◽  
Radical Anion ◽  
Ion Pairs ◽  
Ion Pairing ◽  
Single Electron ◽  
Single Electron Transfer ◽  
Temperature Dependent ◽  
Contact Ion Pairs

The radical anion of dimesityltetraketone (ERed, I = -0.40 V) is easily generated in THF by potassium mirror/[2.2.2]-cryptand reduction. Its contact ion pairs with Na⊕, Cs⊕ and Ba⊕⊕ counter cations, prepared in THF solution by single electron transfer from the respective metals, are characterized by their ESR/ENDOR spectra, which exhibit temperature-dependent metal couplings of aNa⊕ = 0.061 mT (190 K), aCs⊕ = 0.021 mT (190 K), and aBa⊕⊕ = 0.145 mT (295 K).

PHONON BROADENING OF IMPURITY SPECTRAL LINES: III. DIAGRAM TECHNIQUE

1966 ◽  
Vol 44 (1) ◽  
pp. 109-138 ◽  
Author(s):  
Robert Barrie ◽  
R. G. Rystephanick
Keyword(s):  
Shape Function ◽  
Particle Temperature ◽  
Spectral Lines ◽  
Diagram Technique ◽  
Temperature Dependent ◽  
Impurity Potential ◽  
Method Of Calculation ◽  
Double Time ◽  
Particle Propagator ◽  
Temperature Green’S Function

The theory of the phonon broadening of optical absorption lines associated with impurities in semiconductors is discussed, using the diagram technique for the evaluation of an appropriate two-particle temperature Green's function. The single-particle propagator for an electron moving in the impurity potential and simultaneously in interaction with the phonons is calculated and used. The interaction with the phonons is treated as weak. The line-shape function is found, and a comparison is made between this method of calculation and a previous one based on the decoupling of an infinite hierarchy of equations for double-time temperature-dependent Green's functions.

scholarly journals Electron Paramagnetic Evidence for the ·pf3 Radical Anion

2000 ◽  
Vol 2000 (7) ◽  
pp. 342-343 ◽  
Author(s):  
Martyn C.R. Symons
Keyword(s):  
Radical Anion ◽  
Hyperfine Coupling ◽  
Coupling Constants ◽  
Radical Anions ◽  
Epr Spectrum ◽  
Hyperfine Coupling Constants ◽  
Spectroscopic Evidence ◽  
The Third ◽  
Electron Paramagnetic

Although ·PF2 radicals have been extensively studied there does not seem to be any spectroscopic evidence for ·PF3-radical anions. Here it is proposed that an EPR spectrum previously assigned to ·PF2 radicals is almost certainly due to ·PF3-centres. The 31P and 19F hyperfine coupling constants for these radicals are expected to be very similar. However, the ·PF3-radicals should show an extra coupling to the third 19F nucleus. This is clearly present.

Synthesis and magnetic properties of an annulated dinuclear copper(II) phthalocyanine peripherally having 2,6-dimethylphenoxy substituents

2014 ◽  
Vol 18 (08n09) ◽  
pp. 708-714 ◽  
Author(s):  
Takahisa Ikeue ◽  
Naoko Sawada ◽  
Naomi Matsumoto ◽  
Ayaka Miyazaki ◽  
Tamotsu Sugimori ◽  
...  
Keyword(s):  
Benzene Ring ◽  
Dft Calculation ◽  
Toluene Solution ◽  
Temperature Dependent ◽  
Epr Spectrum ◽  
Range Interaction ◽  
Dinuclear Copper ◽  
Long Range Interaction ◽  
The Common ◽  
Dinuclear Structure

A dinuclear copper(II) phthalocyanine complex with 12 2,6-dimethylphenoxyl groups at the peripheral positions of the [ CuPc ]2 framework, where [ CuPc ] units are linked by a common annulated benzene ring to give the planar dinuclear structure, was prepared and characterized. The introduced bulky 2,6-dimethylphenoxyl groups were revealed to effectively suppress the aggregation of the dinuclear complex in the toluene solution, showing a considerably red-shifted Q-band at 838 nm. The EPR spectrum (measured in the frozen toluene solution at 15 K) and temperature-dependent magnetic moment indicated the existence of antiferromagnetic interaction between the copper(II) ions. The exchange integral J was estimated to be -1.8 cm-1 using Bleaney Bowers equation for the S1 = S2 = 1/2 system. The long-range interaction ( Cu – Cu distance = 10.7 Å) through the common annulated benzene ring between two [ CuPc ] units was confirmed by the DFT calculation result.

Shungite Carbon Nanoparticles as Modifiers of Zns:Cu Phosphor, Based on Analysis of the EPR Spectral Lines of Mn+2

2021 ◽  
Vol 1031 ◽  
pp. 201-208
Author(s):  
S.P. Rozhkov ◽  
Natalia N. Rozhkova ◽  
Maxim М. Sychov
Keyword(s):  
Integral Intensity ◽  
Subsurface Layer ◽  
Particle Surface ◽  
Chemical Properties ◽  
Spectral Lines ◽  
Nanoparticle Concentration ◽  
Epr Spectrum ◽  
Physico Chemical ◽  
Saturation Power ◽  
Shungite Carbon

Water dispersions of shungite carbon (ShC) nanoparticles were used for modifying the particle surface of ZnS:Cu, commercial electrophosphor. The EPR spectrum of ZnS:Cu powder has parameters consistent with the paramagnetic centers of Mn+2. Modifying the phodphor surface with ShC nanoparticles results in a non-monotonic change in line width, amplitude and integral intensity caused by nanoparticle concentration, which correlates with variations in the brightness of electroluminescence. Variations in the parameters of spectral lines with nanoparticle concentration and UHF saturation power are interpreted in terms of modification and creation of additional dislocations in the subsurface layer of phosphor with new physico-chemical properties.

Pentanuclear heterobimetallic 3d-4f complexes of Ln2M3-type — structure and magnetism

2008 ◽  
Vol 62 (5) ◽  
Author(s):  
Matthias Siebold ◽  
Maria Korabik ◽  
Uwe Schilde ◽  
Jerzy Mrozinski ◽  
Peter Strauch
Keyword(s):  
Magnetic Properties ◽  
Room Temperature ◽  
Magnetic Moments ◽  
Powdered Sample ◽  
Temperature Dependent ◽  
Epr Spectrum ◽  
Metal Interactions ◽  
Spin Interactions ◽  
Metal Metal ◽  
Complete Series

AbstractFrom a series of pentanuclear, heterobimetallic complexes of the general composition [{Ln(H2O)n}2{Ni(dto)2}3] · xH2O, four complexes (Ln = Gd(III) with n = 4; Ln = Dy(III), Ho(III), or Er(III), with n = 5; x = 9–12; dto = 1,2-dithiooxalate) were studied due to their large magnetic moments (up to 14.65 B.M.). The magnetic properties of these complete series were measured at room temperature and the temperature dependent magnetic properties of the complexes Gd2Ni3, Dy2Ni3, Ho2Ni3, and Er2Ni3 were studied at room temperature down to 1.8 K. Whereas the intramolecular metal-metal distances were rather long (Ni1-Ni2: 11.0–11.5 Å; Ln-Ni: 6.0–6.3 Å), relatively short intermolecular metal-metal distances (Ni1-Ni2′: 3.5 Å; Er-Er′: 6.0 Å) were found in the crystal lattice, giving rise to weak intermolecular metal-metal interactions. These weak spin interactions were also supported by the EPR spectrum of a powdered sample of the diamagnetically undiluted Gd2Ni3 complex.

EPR Spectrum of an Azulene Free Radical Anion

1962 ◽  
Vol 36 (10) ◽  
pp. 2809-2810 ◽  
Author(s):  
Harmon W. Brown ◽  
Robert C. Jones
Keyword(s):  
Free Radical ◽  
Radical Anion ◽  
Epr Spectrum ◽  
Free Radical Anion

Studies on N,N′-Diimidyl Systems by Nuclear Magnetic Resonance Spectroscopy

1974 ◽  
Vol 52 (13) ◽  
pp. 2399-2402 ◽  
Author(s):  
Shiva Mohan Verma ◽  
Kumar Om Prakash Sinha ◽  
Chennupati Koteswara Rao
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Characteristic Feature ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Ground States ◽  
Resonance Spectroscopy ◽  
Temperature Dependent ◽  
Hindered Rotation ◽  
Nuclear Magnetic

A number of N,N′-diimidyl compounds, which possess asymmetry about the imidyl planes, have been synthesized and characterized by n.m.r. and i.r. spectroscopy. The n.m.r. spectra of the compounds were found to be temperature dependent and provide evidence for the hindered rotation about the N—N′ bond. This characteristic feature has been utilized to establish the proposed structures of the products. The asymmetric "cage moieties" have been found useful for the detection of noncoplanar ground states proposed for this system.

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