Analysis of multiple pulse NMR in solids. III

Abstract

A 52-pulse cycle recently introduced in a communication, which has a substantially increased resolving power compared to previously available techniques, is analyzed in detail. Also, a new 24-pulse cycle which is essentially equivalent to the 52-pulse cycle in resolving power is introduced. These pulse cycles achieve their enhanced resolution compared to the REV-S cycle by removing the effects of the homonuclear dipolar interaction in solids to higher orders of magnitude without reintroducing any dipolar terms eliminated by REV-S. Principles of pulse cycle decoupling are introduced which greatly simplify the systematic development of compound mUltiple pulse cycles. Beginning with the 2-pulse solid echo sequence, we show how these principles could have been used in designing the W AHUHA and REV -S cycles and the 14-pulse cycle recently introduced by Haeberlen. We further demonstrate the application of this method by developing several new pulse cycles, such as a 12-pulse cycle equivalent to the 14-pulse cycle, the 24pulse cycle, and the 52-pulse cycle. Finally, proton chemical shift tensor components for several organic solids which were measured using the 52-pulse cycle are reported without detailed discussion.(2) and 944

Robust dynamical decoupling

“…The first approach was introduced in NMR, e.g. for designing high-performance homonuclear decoupling sequences [38][39][40][41][42][43] or in high-resolution heteronuclear decoupling [31][32][33][35][36][37]. Examples of DD sequences that can be constructed using this approach are the XY-8 and XY-16 sequences [36].…”

SIMPSON: A general simulation program for solid-state NMR spectroscopy

“…This may be the case for desired as well as undesired terms of the Hamiltonian implying that accurate determination of structural parameters from the desired terms as well as evaluation of the multiple-pulse building blocks providing suppression of undesired terms very often depend on the ability to numerically simulate the spin dynamics of the actual NMR experiment. This applies, for example, to the solid-state NMR experiments for which dipolar recoupling (e.g, rotational resonance [16,17], REDOR [18], DRAMA [19], DRAWS [20], RFDR [21], RIL [22], HORROR [23], BABA [24], C7 [25,26], RF-DRCP [27]), multiple-pulse homo-or heteronuclear decoupling (e.g., BR-24 [28], FSLG [29], MSHOT-3 [30], TPPM [31]), cross-polarization [32,33], QCPMG-MAS [34], or MQ-MAS [35] pulse sequences are indispensable building blocks. Thus, considering the very large number of advanced experiments already available, the large number of possible combinations between these, and the rapidly increasing number of new experimental procedures presented every year there is a substantial need for a general and consistent simulation tool to support experiment design, user-specific method implementation, and evaluation of spectral data.…”

Environment-assisted metrology with spin qubits

“…If the modulation is fast compared to the couplings, the effective Hamiltonian over the cycle is well approximated by its average. A simple symmetrization of the pulse sequence [28] can further cancel out the first-order correction, leaving errors that are only quadratic in the product κt c (and do not depend on the total evolution time, which could be given by many cycles) [17]. Figure 4 shows how to incorporate a WAHUHA sequence within the EAM sequence.…”