Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Low-load rotor-synchronised Hahn-echo pulse train (RS-HEPT) H-1 decoupling in solid-state NMR
T2 - factors affecting MAS spin-echo dephasing times
AU - Griffin, John M.
AU - Tripon, Carmen
AU - Samoson, Ago
AU - Filip, Claudiu
AU - Brown, Steven P.
PY - 2007/12
Y1 - 2007/12
N2 - Transverse dephasing times T-2' in spin-echo MAS NMR using rotor-synchronised Hahn-echo pulse-train (RS-HEPT) low-load H-1 decoupling are evaluated. Experiments were performed at 300 and 600 MHz for (CH)-C-13-labelled L-alanine and (NH)-N-15(delta)-labelled L-histidine center dot HCl center dot H2O, together with SPINEVOLUTION simulations for a ten-spin system representing the crystal structure environment of the (CH)-C-13 carbon in L-alanine. For 30 kHz MAS and nu(1)(H-1) = 100 kHz at 300 MHz, a RS-HEPT T-2' value of 17 +/- 1 ms was obtained for (CH)-C-13-labelled L-alanine which is similar to 50% of the XiX T-2' value of 33 +/- 2 ms. Optimum RS-HEPT decoupling performance is observed for a relative phase of alternate RS-HEPT pi-pulses, Delta phi = phi' - phi, between 40 and 60 degrees. For experiments at 600 MHz and 30 kHz MAS with (CH)-C-13-labelled L-alanine, the best RS-HEPT (nu(1)(H-1) = 100 kHz) T-2' value was 3 times longer than that observed for low-power continuously applied sequences with nu(1)(H-1)
AB - Transverse dephasing times T-2' in spin-echo MAS NMR using rotor-synchronised Hahn-echo pulse-train (RS-HEPT) low-load H-1 decoupling are evaluated. Experiments were performed at 300 and 600 MHz for (CH)-C-13-labelled L-alanine and (NH)-N-15(delta)-labelled L-histidine center dot HCl center dot H2O, together with SPINEVOLUTION simulations for a ten-spin system representing the crystal structure environment of the (CH)-C-13 carbon in L-alanine. For 30 kHz MAS and nu(1)(H-1) = 100 kHz at 300 MHz, a RS-HEPT T-2' value of 17 +/- 1 ms was obtained for (CH)-C-13-labelled L-alanine which is similar to 50% of the XiX T-2' value of 33 +/- 2 ms. Optimum RS-HEPT decoupling performance is observed for a relative phase of alternate RS-HEPT pi-pulses, Delta phi = phi' - phi, between 40 and 60 degrees. For experiments at 600 MHz and 30 kHz MAS with (CH)-C-13-labelled L-alanine, the best RS-HEPT (nu(1)(H-1) = 100 kHz) T-2' value was 3 times longer than that observed for low-power continuously applied sequences with nu(1)(H-1)
KW - NMR
KW - H-1
KW - C-13
KW - N-15
KW - MAS
KW - spin-echo
KW - low-load H-1 decoupling
KW - dephasing times
KW - BOND CARBON-CARBON
KW - X-RAY-DIFFRACTION
KW - MAGNETIC-RESONANCE-SPECTROSCOPY
KW - C-13-C-13 J-COUPLINGS
KW - CROSS-POLARIZATION
KW - NEUTRON-DIFFRACTION
KW - QUADRUPOLAR NUCLEI
KW - DISORDERED SOLIDS
KW - SHIFT CORRELATION
KW - SCALAR COUPLINGS
U2 - 10.1002/mrc.2145
DO - 10.1002/mrc.2145
M3 - Journal article
VL - 45
SP - S198-S208
JO - Magnetic Resonance in Chemistry
JF - Magnetic Resonance in Chemistry
SN - 0749-1581
IS - S1
ER -