Application of Rotor-Synchronized Amplitude-Modulated Cross-Polarization in a13C–1H Spin Pair under Fast Magic-Angle Spinning

✍ Scribed by Jésus Raya; Jérôme Hirschinger

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 205 KB
• Volume: 133
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.1998.1488

✦ Synopsis

Rotor-synchronized amplitude-modulated Hartmann-Hahn crosspolarization has been applied under fast magic-angle spinning to a powder sample of ferrocene. The influence on the cross-polarization process of the heteronuclear double quantum (flop-flop) transitions induced by the amplitude modulation for low ratios of the radiofrequency-field strength to the spinning speed is studied in details. The experimental data are in good agreement with theoretical calculations for a two-spin 1 2 system, although the intensity of the double quantum transitions is observed to be significantly smaller than expected. Moreover, it is shown that an efficient polarization transfer at the Hartmann-Hahn centerband matching condition as well as a broadening of the matching conditions is obtained by an appropriate partial scaling of the effective radiofrequency fields which minimizes the destructive effect of double quantum cross-polarization.