Proton polarization transfer enhancement for a nucleus with arbitrary spin quantum number from n scalar coupled protons for arbitrary preparation times

Abstract

Polarization transfer enhancement of the NMR resonance from a nucleus with spin quantum number l (l = 1 2 , 1, 3 2 , …) from n scalar coupled protons using the pulse sequence (90 xH)-τ-(180 xH)(180 xI)-τ-(90 yH)(90 xI)-Δ-(acquire with or without H decoupling) is studied theoretically. It is shown that the enhancement of the components of the I multiplet varies with τ as Σ m I m I sin (4 πJm I τ) where J is the scalar coupling constant and m I takes the values l, l - l, …, -l. Values of τ opt which result in the maximum enhancement are calculated, as well as the size of these maximum enhancements. Values of Δ opt which yield the maximum decoupled signal are also computed, along with the maximum decoupled enhancements. The theory is confirmed experimentally for l = 3 2 and l = 3 by studying proton polarization transfer spectra of the 10B and 11B resonances in NaBH 4.