High spins resonance detection

Hartmann T, Ober D (2000) Biosynthesis and Metabolism of Pyrrolizidine Alkaloids in Plants and Specialized Insect Herbivores. 209 207-243 Haseley SR, Kamerling JP, Vliegenthart JFG (2002) Unravelling Carbohydrate Interactions with Biosensors Using Surface Plasmon Resonance (SPR) Detection. 218 93-114 Hassner A, see Namboothiri INN (2001) 216 1-49 Hauser A (2004) Ligand Field Theoretical Considerations. 233 49-58 Hauser A (2004) Light-Induced Spin Crossover and the High-Spin Low-Spin Relaxation. 234 155-198... 

This mechanism leads to a highly spin-polarized triplet state with a characteristic intensity pattern in the EPR spectrum, which is observed by time-resolved techniques (either transient or pulse EPR). The zero field splitting (ZFS) of the triplet state, which dominates the EPR spectrum, is an important additional spectroscopic probe. It can also be determined by optical detection of magnetic resonance (ODMR), for a review of the techniques involved and applications see reference 15. These methods also yield information about dynamical aspects related to the formation, selective population and decay of the triplet states. The application of EPR and related techniques to triplet states in photosynthesis have been reviewed by several authors in the past15 22-100 102. The field was also thoroughly reviewed by Mobius103 and Weber45 in this series. 

In principle the deviation <5 can be determined by the use of usual analytical chemistry or a highly sensitive thermo-balance. These methods, however, are not suitable for very small deviations. In these cases the following methods are often applied to detect the deviation physico-chemical methods (ionic conductivity, diffusion constant, etc.), electro-chemical methods (coulometric titration, etc.), and physical methods (electric conductivity, nuclear magnetic resonance, electron spin resonance, Mossbauer effect, etc.), some of which will be described in detail. 

As a means of identifying the potent oxidant another approach was made. By the use of certain organic compounds one can infer the presence of a free radical by converting a highly unstable one such as OH to a much more stable compound which can accumulate in solution, rendering its detection by electron spin resonance possible. To measure the presence of OH the compound DMPO (5,5-dimethyl l-pyrroline-N-oxide) has been used The characteristic adduct of OH with... 

Instrumentation. Two electron spin resonance spectrometers have been used in the course of the work. The Southampton instrument was built in the laboratory, using a Varian magnet, and operated at 3 cm. wavelength. It employed an Hon rectangular cavity and obtained high sensitivity by magnetic field modulation at 100 kc.p.s. with a crystal detector phase sensitive detection... 

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