title: Sensitivity-enhanced phase-corrected ultra-slow magic angle turning using multiple-echo data acquisition.
abstract: The increase in the sensitivity of the phase-corrected magic angle turning (PHORMAT) experiment at ultra-slow spinning rates by means of multiple-echo data acquisition (ME-PHORMAT) is evaluated. This is achieved by replacing the acquisition dimension in the original experiment with a train of equally spaced pi-pulses. It is shown that the echoes following the odd and even pi-pulses in the CPMG train must be processed differently in order to avoid spectral distortions. The method is illustrated for 13C CP-ME-PHORMAT on solid 1,2,3-trimethoxybenzene and for 1H ME-PHORMAT on excised rat liver tissue, both at a sample-spinning rate of 1.3 Hz. Sensitivity enhancements of a factor 4 for the solid and 2.3 for the liver were obtained. Finally, it is shown that with ME-PHORMAT one of the two RF pulse sequences, in standard PHORMAT used to obtain a pure absorption mode 2D spectrum, can be eliminated, thus reducing the usually long measuring time by a factor 2.
authors.affiliation: Pacific Northwest National Laboratory, PO Box 999, MS K8-98, Richland, WA 99352, USA.
authors.forename: Jian Zhi
authors.initials: JZ
authors.lastname: Hu
authors.forename: Robert A
authors.initials: RA
authors.lastname: Wind
mesh_terms: D000465:Algorithms; D000818:Animals; D000840:Anisoles / Q000737:chemistry; D002247:Carbon Isotopes; D003198:Computer Simulation; D046508:Culture Techniques; D005240:Feasibility Studies; D008099:Liver / Q000737:chemistry* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008280:Magnetics; D008297:Male; D011506:Proteins / Q000737:chemistry / Q000378:metabolism; D011522:Protons; D011786:Quality Control; D011846:Radio Waves; D051381:Rats; D015203:Reproducibility of Results; D012399:Rotation; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D013113:Spin Labels
chemical_list: D000840:Anisoles; D002247:Carbon Isotopes; D011506:Proteins; D011522:Protons; D013113:Spin Labels; C060998:anisole