Spin conversion experimental dependence

However, if the spin conversion measured in the dimensionless parameter y = itdeviations from the linearity (Fig. 3.78). Only at y = 105 is the general dependence (3.631)-(3.633) quasilinear, approaching all the experimental points. 

According to this sequence, formation of cis- and trani -stilbenes is preceded by formation of a magnetosensitive ion-radical by a singlet-triplet conversion. This means that spin polarization must be observed in cis- and trani -stilbene, and the isomerization rate must depend on the intensity of the magnetic held. These predictions were conhrmed experimentally (Lyoshina et al. 1980). Hence, the ion-radical route for trans —f cis conversion is the main one under photoirradiation conditions. Until now, the mechanisms assumed for such processes have involved energy transfer and did not take into account single-electron transfer. The electron transfer takes place in reality and makes the... 

We conclude that zero-order crossing of potential curves can enhance spin-forbidden processes. Spin-forbidden processes, such as intersystem crossing, may also occur in the absence of zero-order crossings, though at a slower rate in general. The formulation here is time dependent. Some experimental phenomena which have been interpreted as time-dependent phenomena (for example, S2 > S1 internal conversion) may also be interpreted in a time-independent188,199 formulation. 

Hyperfine coupling constants provide a direct experimental measure of the distribution of unpaired spin density in paramagnetic molecules and can serve as a critical benchmark for electronic wave functions [1,2]. Conversely, given an accurate theoretical model, one can obtain considerable information on the equilibrium stracture of a free radical from the computed hyperfine coupling constants and from their dependence on temperature. In this scenario, proper account of vibrational modulation effects is not less important than the use of a high quality electronic wave function. 

We found a positive ADMR signal at 0.45 eV that is associated with the photogenerated 5". As mentioned in Section III.B.5, however, a situation where a spinless particle shows an ADMR signal is not uncommon in ODMR spectroscopies. This comes about via spin-dependent recombination processes of companion excitations having a cross-recombination channel with the spinless particle. The experimental correlation found between 6N(HE) (<0) and SN(LE) (>0) may show that an apparent conversion process from into 5 -5 ... 

Two such processes are the excitation of either thermal crystal lattice oscillations (spin-lattice relaxation) and/or excitement of oscillation in the nuclear magnetic system (spin-spin relaxation). Both processes are characterized by constants 7T and T2 71 is the spin-lattice relaxation time and T2 is the spin-spin relaxation time. Valnes of 71 and T2 render an essential influence upon the form of resonance curves. On the other hand, the relaxation processes depend on the mobility of one atomic group or another in the substance. So, experimental measurement of the relaxation processes serves as a method of measurement of the dynamics of chemical conversions depending on time, temperature, chemical conversion particularity and other factors. 

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