Nuclear spin decoupling

Nuclear spin decoupling 4.4 two rf fields 2.5 Assignment of ENDOR transitions... 

Nuclear spin decoupling in ENDOR may be used to facilitate the analysis of complicated ENDOR spectra. Some of the applications are40 ... 

Fig. 19 a, b. Nuclear spin decoupling in ENDOR. a) ENDOR spectrum of Cu(gly)2 in a-glycine vp free proton frequency, b) Decoupling sequence of the doublet structure of the proton H2 (I nucleus) for various pumping fields B2eff at H3 (K nucleus). (Ref. 40)... 

During the last few years the versatility of ENDOR spectroscopy has been improved by a number of new techniques which make use either of special types of pumping fields (CP-ENDOR, PM-ENDOR), of more than one rf field (DOUBLE ENDOR, multiple quantum transitions, nuclear spin decoupling) or a different display of the spectrum (EI-EPR). In addition to these techniques, alternative methods have been developed (electron spin echo and electron spin echo ENDOR) which are able to supplement or to replace the ENDOR experiment under certain conditions. The utility of all these various advanced techniques, particularly in studies of transition metal compounds, has recently been demonstrated. 

The basis set will be that used earlier with the addition of nuclear spin-decoupled... 

The presence of two nuclear spins means that there is considerable choice in the selection of basis functions the reader who wishes to practice virtuosity in irreducible tensor algebra is invited to calculate the matrix elements in the different coupled representations that are possible In fact the sensible choice, particularly when a strong magnetic field is to be applied, is the nuclear spin-decoupled basis set t], A N, S, J, Mj /N, MN /H, MH). Again note the possible source of confusion here MN is the space-fixed component of the nitrogen nuclear spin /N, not the space-fixed component of N. This nuclear spin-decoupled basis set was the one chosen by Wayne and Radford in their analysis of the NH spectrum. 

Nuclear spin decoupling has been widely applied in NMR to simplify complicated spectra in liquid and solid phases . Recently, similar decoupling effects have been observed in single crystal ENDOR spectra with resolved nuclear dipole-dipole couplings between neighboring protons. This interaction can be partially decoupled by a strong second rf field. 

I. Morishkima, T. Inubushi, S. Uemura, and H. Miyoshi. Nitroxide as a nuclear spin decoupling reagent. Application to C n.m.r. studies of organothallium compounds. J. Amer. Chem. Soc., 1978,100, 354. 

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