title: Broad-band homo-nuclear correlations assisted by 1H irradiation for bio-molecules in very high magnetic field at fast and ultra-fast MAS frequencies.
abstract: We propose a new broadband second-order proton-assisted (13)C-(13)C correlation experiment, SHANGHAI. The (13)C-(13)C magnetization transfer is promoted by (1)H irradiation with interspersed four phases super-cycling. This through-space homo-nuclear sequence only irradiates on the proton channel during the mixing time. SHANGHAI benefits from a large number of modulation sidebands, hence leading to a large robustness with respect to chemical shift differences, which permits its use in a broad MAS frequency range. At ultra-fast MAS (ν(R) 60 kHz), SHANGHAI is only efficient when the amplitude of (1)H recoupling rf-field is close to half the spinning speed (ν(1) ≈ ν(R)/2). However, at moderate to fast MAS (ν(R)=20-35 kHz), SHANGHAI is efficient at any rf-power level larger than ν(1) ≈ 10 kHz, which simultaneously permits avoiding excessive heating of bio-molecules, and using large sample volumes. We show that SHANGHAI can be employed at the very high magnetic field of 23.5 T and then allows the observation of correlation between (13)C nuclei, even if their resonance frequencies differ by more than 38 kHz.
authors.affiliation: Physics Department, Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China. bwhu@phy.ecnu.edu.cn
authors.forename: Bingwen
authors.initials: B
authors.lastname: Hu
authors.forename: Oliver
authors.initials: O
authors.lastname: Lafon
authors.forename: Julien
authors.initials: J
authors.lastname: Trébosc
authors.forename: Qun
authors.initials: Q
authors.lastname: Chen
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Amoureux
mesh_terms: D000465:Algorithms; D002247:Carbon Isotopes; D003198:Computer Simulation; D004574:Electromagnetic Fields; D046911:Macromolecular Substances / Q000737:chemistry* / Q000528:radiation effects*; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011522:Protons; D012984:Software
chemical_list: D002247:Carbon Isotopes; D046911:Macromolecular Substances; D011522:Protons