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Systems magnetic resonance sample rotations

Figure 1.48a explains schematically the appearance of resonances between the fixed frequency Figure 1.48a explains schematically the appearance of resonances between the fixed frequency <pl and the different Zeeman components when the magnetic field B is tuned. The experimental arrangement is illustrated in Fig. 1.48b. The sample is placed inside the laser cavity and the laser output is monitored as a function of the magnetic field. The cell is part of a flow system in which radicals are generated either directly in a microwave discharge or by adding reactants to the discharge close to the laser cavity. A polyethylene membrane beam splitter separates the laser medium from the sample. The beam sputter polarizes the radiation and transitions with either AM = 0 or 1 can be selected by rotation of the tube about the laser axis. For illustration. Fig. 1.48c shows the laser magnetic resonance (LMR) spectrum of the CH radical with some OH lines overlapping. Concentrations of 2 X 10 molecules/cm could be stiU detected with reasonable signal-to-noise ratio for the detector time constant of 1 s [141,142].
There are many experimental techniques for the determination of the Spin-Hamiltonian parameters g, Ux, J. D, E. Often applied are Electron Paramagnetic or Spin Resonance (EPR, ESR), Electron Nuclear Double Resonance (ENDOR) or Triple Resonance, Electron-Electron Double Resonance (ELDOR), Nuclear Magnetic Resonance (NMR), occasionally utilizing effects of Chemically Induced Dynamic Nuclear Polarization (CIDNP), Optical Detections of Magnetic Resonance (ODMR) or Microwave Optical Double Resonance (MODR), Laser Magnetic Resonance (LMR), Atomic Beam Spectroscopy, and Muon Spin Rotation (/iSR). The extraction of data from the spectra varies with the methods, the system studied and the physical state of the sample (gas, liquid, unordered or ordered solid). For these procedures the reader is referred to the monographs (D). Further, effective magnetic moments of free radicals are often obtained from static... [Pg.2]

In paramagnetic resonance experiments, the sample is usually placed in a large constant magnetic field H0, whose direction is taken as that of the z axis. This field determines the quantum levels of the individual spins and polarizes them according to Curie s law. In a typical nuclear resonance experiment, a radiofrequency field H1( perpendicular to H0 and rotating in the x,y plane is applied to the sample. The response of the system is, under stationary conditions, described by the radiofrequency susceptibility %(co). The rotating field is given by... [Pg.290]

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