Electron spin relaxation times and internal motions of radicals in the solid state investigated by ENDOR and pulsed EPR

Brustolon, Marina; Maniero, Anna Lisa; Bonora, Marco; Segre, Ulderico

doi:10.1007/bf03163530

Cited by 12 publications

(19 citation statements)

References 15 publications

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“…Information could be obtained by X-band ESEEM on the chemical nature of the atoms establishing the second and higher coordination spheres [8] of Cu e . In these coordination spheres 19F, 23Na, 27A1, 139La (ZBLAN glasses), 23Na, 27A1 (aluminosilicate glasses) and 31 P (phosphate glass) could be detected.…”

Section: Discussionmentioning

confidence: 99%

Pulse EPR spectroscopy of Cu2+-doped inorganic glasses

et al. 1999

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Two-frequency continuous-wave and pulse EPR (electron paramagnetic resonance) spectroscopical techniques are applied to determine static and dynamic EPR parameters of Cu e ions in oxide and fluoride glasses. The investigations are focussed on the analysis of strain effects in the glassy matrices, the identification of the magnetic nuclei in the vicinity of Cu e ions as well as the determination of the dependence of the phase memory time T M on temperature and resonance field. The results obtained by X-band continuous-wave EPR, X-and S-band echo-detected EPR, and X-and S-band electron spin echo envelope modulation studies of Cu e -doped inorganic glasses yield information on the local symmetry of the Cue coordination polyhedra, the chemical nature of the atoms in the second and higher coordination spheres, the distribution of the parameters of the static spin Hamiltonian and the low-temperature motions of the dopant-containing structural units. Special techniques like 2-D Mims ENDOR (electron nuclear double resonance) and hyperfine-correlated ENDOR are applied for the first time to doped inorganic glasses. From the spin relaxation measurements a stronger tendency of the Cu e ' ions to aggregate is found for fluoride glasses in comparison to aluminosilicate and phosphate glasses.

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Section: Discussionmentioning

confidence: 99%

Pulse EPR spectroscopy of Cu2+-doped inorganic glasses

et al. 1999

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“…The resulting values of the dynamical parameters are in good agreement with those obtained for the w1damaged precmsor molecule by previous NMR smdies. 72 …”

Section: Echo Decay and Motionsmentioning

confidence: 97%

Pulsed EPR of Paramagnetic Centers in Solid Phases

Brustolon

Barbon

2003

EPR of Free Radicals in Solids

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“…4.2 K [33]. This motion is reflected in the temperature dependence of the electron spin relaxation times as detected by pulsed-EPR measurements [35]. This motion is reflected in the temperature dependence of the electron spin relaxation times as detected by pulsed-EPR measurements [35].…”

Section: Organic Radicals In Organic Host Crystalsmentioning

confidence: 91%

“…It was also found [28] that radical I was stable at 300 K; demonstrating that upon decay of radical I, radical III is an end-product of the decay of radical II. Example of the couplings for D and 35 Cl deduced are given in Table 4.6. The ENDOR resolution permits small couplings (on the order of 1 MHz due to distant protons) to be precisely measured.…”

Section: Organic Radicals In Organic Host Crystalsmentioning

confidence: 99%

“…Examples of radicals formed at 10 K and 65 K in X-irradiated Radicals formed in -irradiated organic single crystals often exhibit internal motions, methyl groups rotate rapidly and t-butyl group rotate slowly on an ENDOR time scale. Typical examples are given by the study of irradiated 4-methyl-2,6-di-t-butylphenol [35] and irradiated 10-nonadecanone in urea [36] where wobbling of the methylene groups and rotational motion of the radical in the channel were detected. Typical examples are given by the study of irradiated 4-methyl-2,6-di-t-butylphenol [35] and irradiated 10-nonadecanone in urea [36] where wobbling of the methylene groups and rotational motion of the radical in the channel were detected.…”

Section: Organic Radicals In Organic Host Crystalsmentioning

confidence: 99%

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Endor Spectroscopy

Kispert

Piekara-Sady

Handbook of Applied Solid State Spectroscopy

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To understand what electron nuclear double resonance (ENDOR) transitions are, let us consider the energy levels of a system containing one unpaired electron (S = ½) and one nuclear spin (I = ½), as in a hydrogen atom. Since the electron spin and nuclear spin can each be oriented with or against the external magnetic field, there are four possible energy levels as shown in Figure 4.1. The two electron spin eigenfunctions are denoted by e and e , whereas the two nuclear spin wavefunctions are denoted n and n . In the presence of a large external applied field, the selection rule in electron paramagnetic resonance (EPR) is that the electron flips (changes directions) but the nuclear spin does not flip in an EPR transition. Thus, in Figure 4.1, an EPR transition will occur between energy levels 1 and 4 and a second EPR transitions will occur between energy levels 2 and 3. The intensity of the transition between energy levels 1 and 4 will depend on the population differences of these two energy levels. If one then applies a nuclear frequency to the system, which corresponds to either the energy difference between levels 4 and 3 or the difference between lines 2 and 1, one will induce nuclear spin flip that will change the populations in energy levels 4 and 1, respectively. This changes the intensity of the observed EPR signal. This change in intensity is referred to as the ENDOR response. Figure 4.1 Energy diagram for S = 1/2 and I = 1/2.

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Electron spin relaxation times and internal motions of radicals in the solid state investigated by ENDOR and pulsed EPR

Cited by 12 publications

References 15 publications

Pulse EPR spectroscopy of Cu2+-doped inorganic glasses

Pulse EPR spectroscopy of Cu2+-doped inorganic glasses

Pulsed EPR of Paramagnetic Centers in Solid Phases

Endor Spectroscopy

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