Peculiarities of free induction and primary spin echo signals for spin-correlated radical pairs

Keeping in mind ion-radical pairs in a photosynthesis reaction centre first of all, we calculated free induction and spin echo (ESE) signals for an ensemble of radical pairs which initially start in a singlet state. It was shown that the intensity of signals should oscillate depending on the time interval τ between the start of a pair and a microwave pulse forming free induction (FI) or between the start of a pair and the first of two microwave pulses forming primary ESE signal. ESE phase of spin-correlated pairs does not coincide with the corresponding ESE phase of radical pairs in thermal equilibrium. One should also note an interesting feature of FI: immediately after the microwave pulse free induction signal equals zero, and non-zero free induction signal appears only due to spin evolution. This behaviour formally resembles the situation occurring when the primary ESE is formed: a light pulse which creates spin-correlated radical pairs acts as the first microwave pulse in conventional spin echo experiments. Analysis of FI and ESE in experiments on pulse photolysis or radiolysis may provide useful information about the contribution of spin-correlated radical pairs. © 1992 Springer

The magnetoelastic effect in permalloy particles

© 2016, Pleiades Publishing, Ltd.Two independent methods—ferromagnetic resonance and magnetic-force microscopy—have been used to study the magnetoelastic effect in permalloy microparticles. The values of effective magnetic-anisotropy fields that are induced by mechanical compression of microparticles have been obtained from the analysis of ferromagnetic-resonance data. These data have been used to model magnetic-force images of stressed and unstressed particles. The images coincide well with experimentally observed ones

Peculiarities of free induction and primary spin echo signals for spin-correlated radical pairs

Keeping in mind ion-radical pairs in a photosynthesis reaction centre first of all, we calculated free induction and spin echo (ESE) signals for an ensemble of radical pairs which initially start in a singlet state. It was shown that the intensity of signals should oscillate depending on the time interval τ between the start of a pair and a microwave pulse forming free induction (FI) or between the start of a pair and the first of two microwave pulses forming primary ESE signal. ESE phase of spin-correlated pairs does not coincide with the corresponding ESE phase of radical pairs in thermal equilibrium. One should also note an interesting feature of FI: immediately after the microwave pulse free induction signal equals zero, and non-zero free induction signal appears only due to spin evolution. This behaviour formally resembles the situation occurring when the primary ESE is formed: a light pulse which creates spin-correlated radical pairs acts as the first microwave pulse in conventional spin echo experiments. Analysis of FI and ESE in experiments on pulse photolysis or radiolysis may provide useful information about the contribution of spin-correlated radical pairs. © 1992 Springer

Peculiarities of free induction and primary spin echo signals for spin-correlated radical pairs

Keeping in mind ion-radical pairs in a photosynthesis reaction centre first of all, we calculated free induction and spin echo (ESE) signals for an ensemble of radical pairs which initially start in a singlet state. It was shown that the intensity of signals should oscillate depending on the time interval τ between the start of a pair and a microwave pulse forming free induction (FI) or between the start of a pair and the first of two microwave pulses forming primary ESE signal. ESE phase of spin-correlated pairs does not coincide with the corresponding ESE phase of radical pairs in thermal equilibrium. One should also note an interesting feature of FI: immediately after the microwave pulse free induction signal equals zero, and non-zero free induction signal appears only due to spin evolution. This behaviour formally resembles the situation occurring when the primary ESE is formed: a light pulse which creates spin-correlated radical pairs acts as the first microwave pulse in conventional spin echo experiments. Analysis of FI and ESE in experiments on pulse photolysis or radiolysis may provide useful information about the contribution of spin-correlated radical pairs. © 1992 Springer

Peculiarities of free induction and primary spin echo signals for spin-correlated radical pairs

Keeping in mind ion-radical pairs in a photosynthesis reaction centre first of all, we calculated free induction and spin echo (ESE) signals for an ensemble of radical pairs which initially start in a singlet state. It was shown that the intensity of signals should oscillate depending on the time interval τ between the start of a pair and a microwave pulse forming free induction (FI) or between the start of a pair and the first of two microwave pulses forming primary ESE signal. ESE phase of spin-correlated pairs does not coincide with the corresponding ESE phase of radical pairs in thermal equilibrium. One should also note an interesting feature of FI: immediately after the microwave pulse free induction signal equals zero, and non-zero free induction signal appears only due to spin evolution. This behaviour formally resembles the situation occurring when the primary ESE is formed: a light pulse which creates spin-correlated radical pairs acts as the first microwave pulse in conventional spin echo experiments. Analysis of FI and ESE in experiments on pulse photolysis or radiolysis may provide useful information about the contribution of spin-correlated radical pairs. © 1992 Springer

Reversible triplet energy hopping in photo-excited molecules: A two-site model for the spin polarization

The effect of reversible energy hopping between different local environments on the properties of spin-polarized excited states is investigated theoretically using a two-site model. The kinetic equations for the populations of the spin sublevels of the excited state are derived and then used to obtain analytical expressions for the evolution of the spin polarization of excited triplet states under specific conditions. The time dependence of the triplet state polarization patterns is also obtained by numerical solution of the kinetic equations. It is shown that the reversible energy hopping can lead to significant changes in the properties of the triplet state, including changes in the shape of the observed spectrum and, in some cases, the inversion of the sign of the polarization, the generation of the net polarization, and anisotropic spin-lattice relaxation. The relations between the parameters that can be observed experimentally by time-resolved electron paramagnetic resonance spectroscopy and the kinetic and dynamic parameters of the system are discussed

The magnetoelastic effect in permalloy particles

© 2016, Pleiades Publishing, Ltd.Two independent methods—ferromagnetic resonance and magnetic-force microscopy—have been used to study the magnetoelastic effect in permalloy microparticles. The values of effective magnetic-anisotropy fields that are induced by mechanical compression of microparticles have been obtained from the analysis of ferromagnetic-resonance data. These data have been used to model magnetic-force images of stressed and unstressed particles. The images coincide well with experimentally observed ones

The magnetoelastic effect in permalloy particles

© 2016, Pleiades Publishing, Ltd.Two independent methods—ferromagnetic resonance and magnetic-force microscopy—have been used to study the magnetoelastic effect in permalloy microparticles. The values of effective magnetic-anisotropy fields that are induced by mechanical compression of microparticles have been obtained from the analysis of ferromagnetic-resonance data. These data have been used to model magnetic-force images of stressed and unstressed particles. The images coincide well with experimentally observed ones

The magnetoelastic effect in permalloy particles

© 2016, Pleiades Publishing, Ltd.Two independent methods—ferromagnetic resonance and magnetic-force microscopy—have been used to study the magnetoelastic effect in permalloy microparticles. The values of effective magnetic-anisotropy fields that are induced by mechanical compression of microparticles have been obtained from the analysis of ferromagnetic-resonance data. These data have been used to model magnetic-force images of stressed and unstressed particles. The images coincide well with experimentally observed ones