Spin trapping definition

New Acyclic Nitrone Spin Traps. - The range of new acyclic nitrone traps that have been synthesised is more limited than that of the related cyclic materials. Examples of some of these new materials are given in Scheme 3. This is due, at least in part, to the perception that these traps provide more limited data in terms of the range of hyperfine coupling constants than the cyclic nitrones, and hence decreased opportunities for definitive identification of radical adducts. Nonetheless these traps can have considerable advantages in that they often yield very persistent adducts, which can be of major benefit in determining whether a process is radical-mediated or not, before more intensive study to determine the exact nature of the species involved. This persistence is of major importance when the separation and subsequent identification (by other... 

The bulk of the evidence suggests that the answer is yes. No other ESR signature of a deep state has been found (although there is some indication of oxygen-related deep defects in alloys, and possibly a spinless defect in ion-bombarded a-Si H). The defect absorption is proportional to the ESR spin density with the expected transition probability. The DLTS defects are definitely shown to be the same as the 2.0055 defect and further support for the conclusion is found from deep trapping and luminescence data described in Chapter 8. Virtually all the experiments for normal a-Si H can be satisfactorily explained by the ESR-active defect. 

Taking the different arguments together, it is the author s opinion that the dangling bond model remains the more plausible explanation of the 2.0055 defect. Perhaps within a short time, further studies of the hyperfine interaction or calculations of the defect energy levels, etc. will be able to provide definitive proof one way or the other. In the remainder of this book, for the sake of definiteness, we refer to the 2.0055 ESR spin and the associated deep trap as the dangling bond, recognizing that the interpretation of electrical data involves only the gap state levels and the electron occupancy, not the atomic structure. 

The topic of neutral soliton dynamics has been controversial for many years. The reasons have been due to a lack of definite data and a lot of different interpretations from a variety of bases for many experimental data. In this review, we tried to explain most of the important experimental results in terms of a diffuse/trap model based on observations of the ESR linewidth as functions of temperature and frequency. Anomalous broadening observed only in (CH) but not in (CD), at frequencies lower than 6 MHz was explained in a clear-cut way by this model, giving a consistent value of the maximum spin density of the neutral soliton, 0.15-0.17 in comparison with 0.17 determined by the ENDOR technique. These successes represented in the finally obtained diffusion rates which are found to be consistent between NMR and ESR seem to settle the controversy. 

Many systems are being studied to manipulate quantum information. Some make use of individual atoms cold trapped ions, neutral atoms in optical lattices, atoms in crystals. Other involve particle spins or photons in cavity QED or nonlinear optical setups as well as more exotic ones where geometric combinations of elementary excitations are defined as qubits, such as in topological quantum computing [8]. However, none of these systems has yet emerged as a definitive way to build a quantum information processor. A reason for this is that there is an essential dichotomy we need... 

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