title: Detailed analysis of the TIMES and TIMES0 high-resolution MAS methods for high-resolution proton NMR.
abstract: We analyze and compare the specifications of TIMES and TIMES(0) proton high-resolution NMR methods for solid-state samples. This comparison is performed in terms of resolution versus magic-angle spinning (MAS) spinning speed, ν(R), rf-field amplitude, ν(1), and tilt-angle for the effective rf-field, θ(p). The chemical-shift and homo-nuclear dipolar scaling factors are calculated for both methods. For all MAS speeds, the best resolution is always observed with rf-field of ν(1)≈120-130 kHz. At slow MAS speed (ν(R)≤10 kHz), the best resolution is observed for a tilt-angle of θ(P)≈90°. At moderate spinning speed (15≤ν(R)≤35 kHz), θ(P)≈55° gives the best resolution. At higher MAS speed (ν(R)≥60 kHz), with TIMES and TIMES(0) the best resolution is obtained for θ(P)≤40°; but we then recommend TIMES(0), owing to its simpler set-up. We also show that in addition to the usual high rf-field regime (ν(1)≈120-130 kHz), another low rf-regime (ν(1)≈40-50 kHz) exists at MAS speed higher than ν(R)≥60 kHz, which also gives a good (1)H resolution. This low rf-regime should be useful for multi-dimensional analyses of bio-molecules with (1)H detection under high-resolution, in order to limit the heating of the sample.
authors.affiliation: UCCS (CNRS-8181), University Lille North of France, Villeneuve d'Ascq 59652, France.
authors.forename: Xingyu
authors.initials: X
authors.lastname: Lu
authors.forename: Olivier
authors.initials: O
authors.lastname: Lafon
authors.forename: Julien
authors.initials: J
authors.lastname: Trébosc
authors.forename: Aany Sofia Lilly
authors.initials: AS
authors.lastname: Thankamony
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nishiyama
authors.forename: Zhehong
authors.initials: Z
authors.lastname: Gan
authors.forename: P K
authors.initials: PK
authors.lastname: Madhu
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Amoureux
mesh_terms: D000465:Algorithms; D000588:Amines / Q000737:chemistry; D004574:Electromagnetic Fields; D005998:Glycine / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011522:Protons
chemical_list: D000588:Amines; D011522:Protons; D005998:Glycine