ISBN 9783843902328

978-3-8439-0232-8, Reihe NMR-Spektroskopie

Michael Braun
Cooperative Pulses

106 Seiten, Dissertation Technische Universität München (2011), Softcover, A5

Zusammenfassung / Abstract

The present thesis deals with the concept of cooperative (COOP) pulses that are designed to cancel each other’s imperfections and act in a cooperative manner. Multi-scan COOP pulses are applied in several scans and at the same position in a pulse sequence so that undesired signal contributions can be canceled. They complement and generalize phase cycles and difference spectroscopy. We experimentally demonstrate their advantages for broadband and band-selective pulses. Single-scan cooperative (S²-COOP) pulses are applied at different positions of a pulse sequence in a single scan. They can be used to find generalized solutions for common building blocks in NMR spectroscopy. The advantage of the S²-COOP approach is demonstrated in theory and experiment for NOESY-type frequency-labeling blocks. Optimal tracking is a generalization of the gradient ascent pulse engineering (GRAPE) algorithm which allows for the design of pulse sequences that steer the evolution of an ensemble of spin systems such that at defined points in time, a specific trajectory of the density operator is tracked as closely as possible. Optimal tracking has been used for the design of low-power heteronuclear decoupling sequences for in vivo applications. Here, we present the theory of cooperative tracking representing a generalization of optimal tracking and multi-scan COOP pulses. Cooperative tracking pulses, multi-scan and single-scan COOP pulses can be efficiently optimized with extended versions of the GRAPE algorithm.