Cooperative pulses

Viac o knihe

This thesis explores cooperative (COOP) pulses designed to cancel imperfections and function collaboratively. Multi-scan COOP pulses are utilized across multiple scans at the same position within a pulse sequence, enabling the cancellation of unwanted signal contributions. This approach enhances and broadens the applications of phase cycles and difference spectroscopy, demonstrating advantages for both broadband and band-selective pulses. In contrast, single-scan cooperative (S²-COOP) pulses are implemented at various positions within a pulse sequence during a single scan, facilitating generalized solutions for common components in NMR spectroscopy. The efficacy of the S²-COOP method is illustrated through theoretical and experimental results, particularly for NOESY-type frequency-labeling blocks. Additionally, optimal tracking extends the gradient ascent pulse engineering (GRAPE) algorithm, allowing for the design of pulse sequences that guide the evolution of spin systems to closely follow a specific trajectory of the density operator at designated times. This technique has been applied to create low-power heteronuclear decoupling sequences for in vivo uses. The thesis presents cooperative tracking theory, a generalization of both optimal tracking and multi-scan COOP pulses, highlighting that these cooperative tracking pulses, along with multi-scan and single-scan COOP pulses, can be effectively optimized using advanced GRAP