ESR Linewidths of Vanadyl β-Diketonate Complexes in Liquid Solutions

1975 ◽  
Vol 53 (15) ◽  
pp. 1492-1498
Author(s):  
T. E. Eagles ◽  
R. E. D. McClung

The electron spin resonance (ESR) spectra of a series of vanadyl β-diketonate complexes in dilute solutions in several inert solvents have been investigated. The widths of the lines in these spectra have been interpreted in terms of the Kivelson linewidth theory. Significant discrepancies between the experimental linewidths and those predicted by the theory were found at low temperatures and high solvent viscosities. It is concluded that the Stokes–Einstein relationship, which relates the reorientational correlation time to the solvent viscosity, is not valid in the low temperature region and that the simple description of spin relaxation by the spin–rotational interaction given by Atkins and Kivelson is inadequate.

Clay Minerals ◽  
1987 ◽  
Vol 22 (3) ◽  
pp. 287-296 ◽  
Author(s):  
N. Chaikum ◽  
R. M. Carr

AbstractAbsorption lines in the g ∼ 4 region of ESR spectra of three New Zealand halloysites were found to originate from similar paramagnetic centres as in kaolinites. Resonances in the g ∼ 4 region were not common to all the halloysites, although the signal at g = 2·0 for the Matauri Bay halloysite is probably due to a trapped positive hole or trapped ion. A 6-line resonance produced by Te Puke halloysite and removable by Na-saturation is attributed to exchangeable Mn on the clay surface. Low-temperature lines exhibited by all samples are due to V4+ or VO2+ replacing Al3+ in the octahedral sheet.


2012 ◽  
Vol 479-481 ◽  
pp. 270-273
Author(s):  
Yan Ge Zhang ◽  
Pin Jiang Li ◽  
Xiao Yun Zheng ◽  
Wen Jun Fa ◽  
Li Bo Fan ◽  
...  

Single crystalline Mn3O4 nanorods with diameters of 10-200 nm and lengths up to several microns have been synthesized by a simple hydrothermal method at a relatively low temperature. The products have been characterized by microscopic and spectroscopic techniques. From the Electron Spin Resonance (ESR) spectra of the products, hyperfine structure (six absorption peaks of ESR) of Mn2+ ion adding the Mn3+ ion signal was observed and results confirmed the nanorods showed paramagnetic behaviors.


2002 ◽  
Vol 715 ◽  
Author(s):  
J. Whitaker ◽  
T. Su ◽  
P. C. Taylor

AbstractOptically induced electron spin resonance (LESR) studies on time scales in between the previously published PL and LESR results (approximately 10 ms to 10 s) allow one to examine the cross over between energy-loss (downward) hopping of carriers and carrier recombination via tunneling. In addition, data in this time regime are directly compared in the same sample with NMR data on the dipolar spin-lattice relaxation of the bonded hydrogen where light induced electrons and holes are responsible for dipolar relaxation of bonded hydrogen. The LESR results confirm the interpretation of the NMR measurements.


1967 ◽  
Vol 45 (12) ◽  
pp. 1831-1839 ◽  
Author(s):  
W. F. Forbes ◽  
P. D. Sullivan

Polycrystalline amino acids, when irradiated with 2537 Å light, afford a variety of electron spin resonance signals. These signals are generally stable at room temperature for relatively long periods of time. For a number of the spectra obtained, there is evidence that more than one radical species contributes to the observed spectra. The signals obtained frequently differ from those obtained on exposure to ionizing radiation. The postulated species formed can often be visualized as being formed by effective hydrogen abstraction from the alkyl-substituted tertiary carbon atom or from the —OH, —SH or —NH group contained in the side chain. For L-phenylalanine a secondary radical is obtained, which is ascribed to a cyclohexadienyl radical.


1982 ◽  
Vol 36 (1) ◽  
pp. 52-57 ◽  
Author(s):  
L. S. Singer ◽  
I. C. Lewis

The applications of electron spin resonance (ESR) to carbonaceous materials are reviewed. The stable paramagnetic species observed in the products of low-temperature pyrolysis are odd-alternate neutral free radicals, whereas the unpaired spins of higher temperature carbons and graphites are primarily conduction electrons. The variety of ESR properties and phenomena requires special attention to techniques of measurement and interpretations of results. The relevance to the carbonization process of the free radicals observed by ESR is also discussed.


1979 ◽  
Vol 57 (5) ◽  
pp. 600-602 ◽  
Author(s):  
K. S. Chen ◽  
T. Foster ◽  
J. K. S. Wan

Contact radical ion-pairs of ammonium and fluoro-substituted ketones were generated in photochemical systems and their here-to-fore elusive esr spectra were characterized.


MRS Advances ◽  
2018 ◽  
Vol 3 (32) ◽  
pp. 1831-1836
Author(s):  
C. L. Saiz ◽  
E. Castro ◽  
L. M. Martinez ◽  
S. R. J. Hennadige ◽  
L. Echegoyen ◽  
...  

ABSRTACTIn this article, we report low-temperature electron spin resonance (ESR) investigations carried out on solution processed three-layer inverted solar cell structures: PC61BM/CH3NH3PbI3/PEDOT:PSS/Glass, where PC61BM and PEDOT:PSS act as electron and hole transport layers, respectively. ESR measurements were conducted on ex-situ light (1 Sun) illuminated samples. We find two distinct ESR spectra. First ESR spectra resembles a typical powder pattern, associated with gx = gy = 4.2; gz = 9.2, found to be originated from Fe3+ extrinsic impurity located in the glass substrate. Second ESR spectra contains a broad (peak-to-peak line width ∼ 10 G) and intense ESR signal appearing at g = 2.008; and a weak, partly overlapped, but much narrower (peak-to-peak line width ∼ 4 G) ESR signal at g = 2.0022. Both sets of ESR spectra degrade in intensity upon light illumination. The latter two signals were found to stem from light-induced silicon dangling bonds and oxygen vacancies, respectively. Our controlled measurements confirm that these centers were generated during UV-ozone treatment of the glass substrate –a necessary step to be performed before PEDOT:PSS is spin coated. This work forms a significant step in understanding the light-induced- as well as extrinsic defects in perovskite solar cell materials.


1980 ◽  
Vol 3 ◽  
Author(s):  
E. L. Venturini

ABSTRACTElectron spin resonance (ESR) of dilute paramagnetic ions in nonmagnetic metallic hydrides provides microscopic information about the hydrogen ions in the immediate vicinity of the impurity. By comparing ESR spectra for different host metals and several hydrogen/metal ratios, one can determine material properties including host lattice symmetry, phase boundaries and occupation of available sites by hydrogen. Examples are presented of ESR of dilute Er in group IIIB and IVB metal hydrides, demonstrating the sensitivity and versatility of ESR as a spectroscopic technique.


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