FREQUENTLY USED SYMBOLS AND ABBREVIATIONS ., an unpaired electron β Bohr magneton ↑or↓, possible orientations(with respect to Bo) of the agnetic moment of an electron or an 1=, nucleus [] concentration in moles per liter m,n-fold axis of C (I, indicates the nucleus being irradiated in a double- C(A)T, computed(axial)tomography COSY, 2D correlation spectroscopy 2D, NMR spectrum where signal intensity is a function of CSR, chemical shift reagent d, doublet(signal multiplicity) A, (1)mass number of a nucleus; (2)net CIDNP absorption D, deuterium (H) △, a change(eg△E, a change in energy) a, hyperfine coupling constant in an EPR spectrum 8. chemical shift signal position(pp a,(1)one possible orientation(with respect to Bo) of the 811.822, 833. chemical shift tensors magnetic moment of an electron or an /=7 nucleus; (2)the flip angle in a pulsed NMR experiment Aox, substituent shielding parameter Av, frequency difference(Hz) between the signal of inter- AA'BB, Pople designation for a coupled four-spin system est and the operating frequency of the spectrometer: consisting of two chemically but not magnetically also used for electric quadrupole interaction equivalent nuclei in each of two sets Avo, frequency difference(Hz) between two sites at the A/E, absorption-emission CIDNP net effect APT, attached proton test 8v, frequency difference(Hz) between the signal of inter- est and the frequency of the internal standard signal also a measure of spectral resolution Bo, external(applied)magnetic field vector 8r, spatial resolution along x axis B. oscillating magnetic field vector of the observing chan An, field of view along x axis DEPT, distortionless enhancement by polarization transfer B2, oscillating magnetic field vector of the"irradiating DMF, dimethylformamide B, possible orientation( with respect to Bo)of the magnetic moment of an electron or an /=i nucleus E, (I)energy:(2)net CIDNP emission