Polarization optical nuclear

Optical Nuclear Polarization (MI-ONP). Formal Equivalence of Microwave-Induced Level-Anticrossing Optical Nuclear Polarization. Extreme Values for Polarization. 

Applications of Optical Pumping and Polarization Techniques in NMR I. Optical Nuclear Polarization in Molecular Crystals... 

The optical nuclear polarization of quinazoline in hexadeuterobenzene was obtained by irradiation with an SP 1000 Philips lamp. The protons at C-2 and C-4 exhibited very strong and strong absorption polarization, respec-tivdy. The polarization of the hydrogens a to the heteroatoms were governed by the distance between the nitrogen atoms. For comparison, H-2 and H-4 in quinoxaline showed absorption polarization, but H-l and H-4 in phtha-lazine and H-3 and H-4 in cinnoline exhibited no polarization.36... 

A future optical device exploiting these two discoveries could write, read and operate on electron spins, while using patterned magnetic regions as memory elements. The region of large nuclear polarization rotates electron spins as they pass by- one necessary operation for quantum computing."... 

In Eq. [33], cOg denotes a characteristic frequency of the optical excitations of the solvent. The kinetic energy of the nuclear polarization Vn is left out in... 

The proton equilibrium nuclear polarization in liquid samples at room temperature is only of the order of 10. In gaseous samples it is even less due to the reduced number of spins in a unit volume. However, the nuclei of gases such as He and Xe can be prepared in a high state of nuclear polarization ( 10 ) by the well-known technique of optical pumping. Such a high degree of polarization is referred to as hyperpolarization... 

Fig. 3. Jablonski energy-level diagram typical for chromophores involved in ONP processes (specifically for pentacene in naphthalene, after Ref. [39]), showing the respective roles of optical excitation, ISC, OEP, electron-nuclear polarization transfer (here driven by mw radiation), and subsequent decay to the diamagnetic ground state. The relative populations of the triplet magnetic sublevels are given at the far right (assuming the crystal is oriented such that the long molecular axis of pentacene is parallel to the external magnetic field ).

Considerable efforts over the years have been directed towards enhancing the ONP process by driving the electron-nuclear polarization transfer via resonant or near-resonant (rf/mw) AC fields. This practice can not only improve the efficiency of the ONP process (particularly in systems or experimental regimes where LAC-ONP is not possible), but - with implementation of pulsed optical and AC fields - can permit time-resolved studies as well. 

The combination of collinear fast-beam laser spectroscopy and P-RADOP (radiation-detected optical pumping) has been used to measure nuclear spins and moments of neutron-rich isotopes of the light alkali elements jLi [72-74] and Na [75]. Here, the optically pumped fast atomic beam is implanted into a single crystal placed in a static magnetic field. The NMR signal is destroying the nuclear polarization detected by measuring the p-decay asymmetry. 

There are a variety of techniques for the determination of the various parameters of the spin-Hamiltonian. Often applied are Electron Paramagnetic or Spin Resonance (EPR, ESR), Electron Nuclear Double Resonance (ENDOR), Electron Electron Double Resonance (ELDOR), Nuclear Magnetic Resonance (NMR), occassionally utilizing effects of Chemically Induced Dynamic Nuclear Polarization (CIDNP), Optical Detection of Magnetic Resonance (ODMR), Atomic Beam Spectroscopy and Optical Spectroscopy. The extraction of the magnetic parameters from the spectra obtained by application of these and related techniques follows procedures which may in detail depend on the technique, the state of the sample (gaseous, liquid, unordered solid, ordered solid) and on spectral resolution. For particulars, the reader is referred to the general references (D). 

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