Optically directed magnetic resonance

D was determined by measuring the Ams = 2 EPR transition, where ms is the spin quantum number. Several years later, D and E were obtained directly by observation of the Ams = 1 EPR signals/33 1 In 1973, Zuclich et alP redetermined the triplet-state splitting parameters of tyrosine using optically detected magnetic resonance (ODMR) spectroscopy. 

Toward the molecular end of the scale range, PNA has been shown to act as scaffold for transition metal ions situated at the core of PNA duplexes (46) (Fig. 6). The metal ion incorporation was realized by the chemical substitution of nucleobases with ligands. This process is site specific because the ligands have higher affinity for metal ions than the nucleobases. The existence of the metal ions within the PNA duplexes opens the possibility of directional electron transfer mediated by the metal ions, in a manner similar to that in which electron transfer metallo-proteins work in Nature. Also, some of the metal ions enhance electrochemical, optical, or magnetic resonance detection of the PNA strands or duplexes. 

The luminescence properties of siloxene have now been studied in great detail. A typical siloxene PL spectrum is shown at the bottom of Figure 15.4 (b). It has a maximum in the yellow-green spectral range at around 2.4 eV. At low temperatures, a radiative lifetime of 10 ns and a polarization memory were observed. These properties and the small Stokes shift between the photoluminescence and its excitation spectra provide experimental evidence for the hypothesis that siloxene does indeed have a direct band gap. Details of the excited states in siloxene leading to the luminescence have also been obtained from measurements of optically detected magnetic resonance... 

Magnetic and optical resonances are identical electromagnetic phenomena in the sense that there occurs an interaction of a magnetic field with matter, and both types of experiments may be described under a common mathematical formalism that is independent of experimental approach. But in developing a theoretical formalism that fuses both optical and magnetic resonance phenomena there occurs a problem reconciling the manner in which one treats the resonance condition. For example, both magnetic resonance theory and experiment deal directly with an... 

Enantiomers have identical chemical and physical properties in the absence of an external chiral influence. This means that 2 and 3 have the same melting point, solubility, chromatographic retention time, infrared spectroscopy (IR), and nuclear magnetic resonance (NMR) spectra. However, there is one property in which chiral compounds differ from achiral compounds and in which enantiomers differ from each other. This property is the direction in which they rotate plane-polarized light, and this is called optical activity or optical rotation. Optical rotation can be interpreted as the outcome of interaction between an enantiomeric compound and polarized light. Thus, enantiomer 3, which rotates plane-polarized light in a clockwise direction, is described as (+)-lactic acid, while enantiomer 2, which has an equal and opposite rotation under the same conditions, is described as (—)-lactic acid. 

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