title: Composite pulsed field gradients with refocused chemical shifts and short recovery time.
abstract: An improved self-compensating pulsed field gradient (PFG) technique that combines antiphase gradient pairs with broadband frequency-modulated 180 degrees pulses is proposed. The antiphase gradient pairs lead to superb system recovery. In addition, evolution under chemical shift and heteronuclear J coupling are refocused during the PFG, making it appear effectively instantaneous. This new approach makes it possible to obtain high-resolution phase-sensitive 2D spectra for the PFG version of many experiments such as COSY, DQF-COSY, and HSQC without adding extra compensating delays or pulses. While reasonable suppression of unwanted magnetization is achieved, this method also gives satisfactory retention of desired signals. As a bonus, the field-frequency lock is not perturbed during the experiments.
authors.affiliation: Chemistry Department, University of California, Irvine, California, 92697-2025, USA.
authors.forename: H
authors.initials: H
authors.lastname: Hu
authors.forename: A J
authors.initials: AJ
authors.lastname: Shaka
mesh_terms: D002244:Carbon / Q000032:analysis; D007091:Image Processing, Computer-Assisted; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008280:Magnetics; D008956:Models, Chemical; D008962:Models, Theoretical; D015394:Molecular Structure; D011522:Protons
chemical_list: D011522:Protons; D002244:Carbon