A six-pulse PASS MAS-NMR technique solved by a phasor method

The PASS MAS-NMR technique is capable of recovering full intensities of the central resonances of a spectrum by phase adjusting the spinning sidebands. This variant of the original PASS sequence by Dixon uses six pi pulses instead of four. The addition of two pi pulses provides more flexibility in choosing the spacing between pulses and therefore eliminates pulse overlap and receiver dead-time problems. The nonlinear, underdetermined PASS equations were solved using a graphical phasor method. All PASS sequences were successfully tested. A table of the six pulse delay times for different pitches is presented. (C) 1998 Academic Press.