Efficient ¹H-¹H magnetization mixing at ultrafast MAS

Homonuclear dipolar interactions should be recoupled to achieve ¹H-¹H magnetization mixing at ultrafast MAS where the dipolar interactions are largely suppressed. Radio Frequency Driven Recoupling (RFDR) is widely used zero-quantum dipolar recoupling method for ¹³C and can be used for ¹H as well. While (XY8)4¹ is the best phase cycling for ¹³C, it is not obvious what is the best for ¹H. There is two criteria: 1) better conservation of overall ¹H magnetization and 2) efficient magnetization transfer between ¹Hs. The best is found to be XY4 for low power (～100 kHz) and XY4¹₄ for high power (～400 kHz).

Reference

Y. Nishiyama, R. Zhang, A. Ramamoorthy, J. Magn. Reson. 243 (2014) 25-32
*This research was supported by funds from NIH (GM084018 and GM095640 to Prof. A. Ramamoorthy).