Extracting Scalar Couplings From Complex H NMR Spectra Using a Simple 2D J-Resolved Sequence.

Measurement of scalar couplings between protons is a very challenging task because of complex multiplet patterns and severe overlapping of these multiplets in congested 1D spectra. Numerous 2D J-resolved sequences now exist that utilize either the Zangger-Sterk or PSYCHE or z-filter elements along with selective refocusing and pure-shift schemes to generate high-resolution phase-sensitive spectra with simple doublets in dimension. Herein, we present a 2D J-resolved sequence that employs a simple element consisting of hard pulses and inter-pulse delays to generate phase-sensitive spectra.

Excitation of long-lived nuclear spin order using spin-locking: a geometrical formalism.

Over the last two decades, numerous pulse sequences have been introduced for the excitation of long-lived spin order (LLS) in high fields. The long continuous wave (CW) or adiabatic pulses used in the SLIC and APSOC sequences should remind one of the spin-locking pulses that are used to induce cross-polarization (CP). Dynamics during these spin-lockings in CP experiments are explained through a geometrical formalism.