NMR spectroscopy in inhomogeneous B0 and B1 fields with non-linearcorrelation

Journal Article · Sat Jan 01 04:00:00 EST 2005 · Journal of Magnetic Resonance

DOI:https://doi.org/10.1016/j.jmr.2005.03.006· OSTI ID:878690

Topgaard, Daniel; Sakellariou, Dimitris; Pines, Alexander

Resolved NMR spectra from samples in inhomogeneous B0 and B1 fields can be obtained with the so-called ''ex situ'' methodology, employing a train of composite or adiabatic z-rotation RF pulses to periodically refocus the inhomogeneous broadening during the detection of the time-domain signal. Earlier schemes relied on a linear correlation between the inhomogeneous B0 and B1 fields. Here the pulse length, bandwidth, and amplitude of the adiabatic pulses of the hyperbolic secant type are adjusted to improve the refocusing for a setup with non-linear correlation. The field correlation is measured using a two-dimensional nutation experiment augmented with a third dimension with varying RF carrier frequency accounting for off-resonance effects. The pulse optimization is performed with a computer algorithm using the experimentally determined field correlation and a standard adiabatic z-rotation pulse as a starting point for the iterative optimization procedure. The shape of the z-rotation RF pulse is manipulated to provide refocusing for the conditions given by the sample-, magnet-, and RF coil geometry.

• Research Organization: Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
• Sponsoring Organization: USDOE Director. Office of Science. Office of Basic EnergySciences; Swedish Research Council Fellowship Grant
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 878690
• Report Number(s): LBNL--57175; BnR: KC0203010
• Journal Information: Journal of Magnetic Resonance, Journal Name: Journal of Magnetic Resonance Journal Issue: 1 Vol. 175; ISSN 1090-7807; ISSN JMARF3
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALGORITHMS
AMPLITUDES
COMPUTERS
DETECTION
DIMENSIONS
GEOMETRY
Inhomogeneous magnetic fields chemical shift numericaloptimization adiabatic pulses z-rotation
NMR SPECTRA
OPTIMIZATION
SHAPE
SPECTROSCOPY