Ramped-Amplitude Cross Polarization in Magic-Angle-Spinning NMR Export

@article{citeulike:2049800, abstract = {The Hartmann-Hahn matching profile in CP-MAS NMR shows a strong mismatch dependence if the MAS frequency is on the order of the dipolar couplings in the sample. Under these conditions, the profile breaks down into a series of narrow matching bands separated by the spinning speed, and it becomes difficult to establish and maintain an efficient matching condition. Variable-amplitude CP (VACP), as introduced previously (Peersen et al., J. Magn. Reson. A104, 334, 1993), has been proven to be effective for restoring flat profiles at high spinning speeds. Here, a refined implementation of VACP using a ramped-amplitude cross-polarization sequence (RAMP-CP) is described. The order of the amplitude modulation is shown to be of importance for the cross-polarization process. The new pulse sequence with a linear amplitude ramp is not only easier to set up but also improves the performance of the variable-amplitude experiment in that it produces flat profiles over a wider range of matching conditions even with short total contact times. An increase in signal intensity is obtained compared to both con ventional CP and the originally proposed VACP sequence.}, author = {Metz, G. and Wu, X. L. and Smith, S. O.}, citeulike-article-id = {2049800}, citeulike-linkout-0 = {http://dx.doi.org/10.1006/jmra.1994.1208}, citeulike-linkout-1 = {http://www.sciencedirect.com/science/article/B6WJY-45P09K9-1B/2/cf33bef1f3a560e185ef195fe2c1d3e6}, doi = {10.1006/jmra.1994.1208}, journal = {Journal of Magnetic Resonance, Series A}, keywords = {cross\_polarization, ssnmr}, month = {October}, number = {2}, pages = {219--227}, posted-at = {2007-12-03 13:23:55}, priority = {2}, title = {Ramped-Amplitude Cross Polarization in Magic-Angle-Spinning NMR}, url = {http://dx.doi.org/10.1006/jmra.1994.1208}, volume = {110}, year = {1994} }

TY - JOUR ID - citeulike:2049800 L3 - citeulike-article-id:2049800 N2 - The Hartmann-Hahn matching profile in CP-MAS NMR shows a strong mismatch dependence if the MAS frequency is on the order of the dipolar couplings in the sample. Under these conditions, the profile breaks down into a series of narrow matching bands separated by the spinning speed, and it becomes difficult to establish and maintain an efficient matching condition. Variable-amplitude CP (VACP), as introduced previously (Peersen et al., J. Magn. Reson. A104, 334, 1993), has been proven to be effective for restoring flat profiles at high spinning speeds. Here, a refined implementation of VACP using a ramped-amplitude cross-polarization sequence (RAMP-CP) is described. The order of the amplitude modulation is shown to be of importance for the cross-polarization process. The new pulse sequence with a linear amplitude ramp is not only easier to set up but also improves the performance of the variable-amplitude experiment in that it produces flat profiles over a wider range of matching conditions even with short total contact times. An increase in signal intensity is obtained compared to both con ventional CP and the originally proposed VACP sequence. IS - 2 JF - Journal of Magnetic Resonance, Series A EP - 227 TI - Ramped-Amplitude Cross Polarization in Magic-Angle-Spinning NMR VL - 110 SP - 219 KW - cross_polarization KW - ssnmr AU - Metz, G AU - Wu, XL AU - Smith, SO PY - 1994/10// UR - http://dx.doi.org/10.1006/jmra.1994.1208 ER -